Infrastructure to allow refuelling EVs is growing, but with EVs, recharging at home will remain most important. Fully benefiting from getting an EV, requires understanding and the right preparation for recharging.
Most of this page is all about the background to the following key points, and while much explanation is required to full get why, the key points are:
- Unlike filling up with gas/petrol, if the answer to “what are you doing right now?”, is ever “charging”, you are not doing it right.
- Most people, for all but around the 2 weeks per year of ‘road trips’, will ideally only need to charge at home.
- Home charging is the least expensive, and most convenient option, and for most people, only requires access to a regular mains power socket.
- Road trip charging, does not match ‘refuelling’ (which for EVs, is battery swapping) and recharging :
- is, although slower, less expensive than refuelling
- is likely to become more widely available than refuelling ever has been as less infrastructure is required
- can even save time if ‘recharging’ the driver (and family) is done while charging the EV
- but…there are many details to getting charging right with today’s EVs.
Key Concepts Of Charge For Electric Vehicles (EVs)
You Can Refuel An EV Instead Of Recharge, And It Is Faster, But Do You Want To?
Many people start with the idea that recharging an EV is just like the new way
Refuelling is replacing the previously used, and now “spent”, fuel with new fuel in a charged state. For an EV, is battery swapping. Just put in a new battery so the fuel supply is just like it was before the old battery was discharged. This is the true equivalent of filling up with gas. When you adjust to the difference, recharging is better, but until then, it can seem worse.
Recharging is adding energy to restore the “spent” fuel, back to its initial state. With fossil fuels, this requires huge areas of land to grow the plants that get the CO2 back from the air, and eventually use the energy from sunlight create oil underground from the same chemicals as are in car exhaust. But with batteries, we keep the “exhaust” inside the battery and can recharge in just hours, and amazingly, even do a fast recharge in just minutes!
In fact you can refuel some EVs, as battery swapping, previously championed but later rejected by Tesla, may be making a comeback. But with EVs, recharging is possible, and on most occasions, can provide a much better experience than the refuelling we are familiar with, even if there are situations where that more familiar, and faster, refuelling experience, may still be the best option. EVs enable a choice, and even if you feel refuelling (battery swapping) is how you would like to replace charge, it still makes sense to understand the alternative that most people prefer most of the time.
When asked about battery-swapping technology, Volkswagen spokesperson Mark Gillies told Car and Driver, “Our data indicates that only 3 to 5 percent of all EV drivers use fast charging as an option to get juice in their battery.” In other words, most people are still charging at home at night for their daily driving.Car and Driver: Aug 2020
Teslas were at one time all designed to accommodate battery swapping, but it was just not popular, as stated by Elon Musk:
It’s just, people don’t care about pack swap. The Superchargers are fast enough that if you’re driving from LA to San Francisco, and you start a trip at 9AM, by the time you get to, say, noon, you want to stop, and you want to stretch your legs, hit the restroom, grab a bite to eat, grab a coffee, and be on your way, and by that time, the car is charged and ready to go, and it’s free. So, it’s like, why would you do the pack swap? It doesn’t make much sense.The Verge, 2015: Tesla sounds ready to pull the plug on promised battery-swap technology
‘Supercharging’ is no longer free for most people, but it logically will always be less expensive than battery swapping.
In China, people are using battery charging, but there are a lot of people. Different demographic, different time, different housing and driving patterns, but most of all, a far larger sample of people in China drive EVs today than drove EVs in California in 2015. Taking VWs data of 3% to 5% of people using fast charging as the target market, then for one brand of EV in the Chinese market to have enough customers for the service does not mean it will find enough customers everywhere.
The entire focus of battery swapping is mainly for road trips, and for when charging at home is not possible.
Even those who make use of battery swapping (refuelling), normally recharge their battery at home or work when not on a road trip, and almost always prefer the lower cost and greater convenience of recharging when not on a “road trip”.
So battery swapping exists and may become more available, but is something to use some of the time, because if you own an EV, you are almost certainly going to find recharging more convenient and less expensive almost all the time.
Fuel Requires A Supply Chain, But Charge (Energy) Is Everywhere.
A first, it seems recharging is the equivalent to refuelling fossil fuels, but on reflection it is battery swapping swapping that is the equivalent to refuelling fossil fuels, as this replacing spent fuel with new fuel. Recharging is not practical with fossil fuels, partly because the ‘spent’ fuel or exhaust isn’t captured, but also because restoring it back to its original state is really slow.
Being able to recharge the fuel means you do not need new ingredients, only energy. Ok, you could call energy an ingredient, but as it is not a substance, which makes it fundamentally different. You can get it in very different ways, can even make it yourself, and do not need to got to a specific type of provider to purchase it. There is no need to mine it somewhere, and no single source of supply. Energy is ubiquitous. Every country can make energy. Today, not only is the electric grid connected to almost every home and office, but as those homes not connected to the grid still receive solar energy, they still have access to energy, and can have electricity.
While refilling a fossil fuel tank, or battery swapping an electric car, requires a visit to as special “fuel station” (or swap station), you do not need to go to a special place to get energy or charge, as it is continually delivered homes offices and anywhere people live. Even places not connected to the grid receive solar energy.
While the best range per day obtainable from solar power with a car today is around 64 kms (40 miles), which fortunately is within the distance most people drive on average per day. Note, that is the range gained from the sun each day, but the Aptera can store 20 days of energy from sunshine, allowing a drive 1,600km (1,00 miles) in a single day once charged. The point is that even in the event of an apocalypse, every one with a solar blanket can still drive their electric car, even only a limited distance each day.
Many problems can disrupt the supply of fossil fuel, but the very nature of the electric grid means long term disruption of electrical supply to a wide area is far less likely, and there are even off the grid solutions.
Like With Your Phone, Normal Life Means Recharging While Sleeping.
In some ways The analaogy need to think more like mobile phone recharging than like traditional refuelling, which is quite an adjustment.
Charging while sleeping, the ideal for an electric vehicle, will normally mean that overnight, vehicle is recharged enough replace whatever charge was used during the day, or at least ensuring more than sufficient charge for the entire next day. For most of us, this is just like what happens with a mobile phone.
Normally, the car battery will only need a top up each night, not a full charge, as how often would need to refuel an internal combustion vehicle on days you start with a full tank? The full tank used within a day! Generally, this only happens when on a road trip.
While there are many reasons for only wanting a refuel stop around once a week, there is little reason not to plus in after parking every night if it is possible.
For those where plugging in at night is not possible, EV ownership is way less satisfying.
Of course, just as some phones just don’t last all day if you watch lots of videos or some other battery intensive activity and could need an emergency top-up. Same with electric vehicles. While all early vehicles had terrible range, now even the least expensive EVs that sell for around US$5,000 in China can get at least 250km (150 miles). Given a normal person averages less than 60km per day (See charging systems reference), a range of even 250km should provide for even quite unusual days. Most days cars are used just for local transport, but for a road trip or for an ’emergency’ when the driver just didn’t get to recharge as they should, rapid charging at charging stations will be the solution until in road wireless charging is available.
Rapid Charge At Charging Stations: Emergency Charging and Road Trips.
Many people focus almost entirely on rapid charging before buying an electric car, but with the exception of those who drive all day during their employment, almost everyone then almost never uses rapid charging. Perhaps with exception of car reviewers, who often do have employment that results in often spending most of the day driving.
Just as you need to consider how you will charge your phone on a trip, you need a different arrangement when on a trip with your car. Now if you were watching videos all day on your phone on your trip, you may need to charge your phone more than once a day, and if you are going to be doing far more driving than normal on your trip, you will need to charge your car one a day. For both phone and car “rapid charging” become important.
Use of rapid charging should be very rare, unless a person either:
- Has an unsuitable car.
- Road test cars as an occupation, or has other commercial use.
- Has free access to rapid charging, or doesn’t have the ability to charge at home.
A car needing rapid charge, is in some ways like a person who did not get enough sleep last night, and as a result needs a ‘catnap’ to get through the day. Either the day is unusually tiring, or the person is not getting enough sleep. Frequent use of rapid or emergency charging creates problems because:
- Rapid chargers are additional infrastructure that comes at a cost, increasing the cost of electricity.
- Using a rapid charger frequently will reduce battery life.
For lowest running costs, best battery life, and the best experience from an EV, almost all charging should be at home and rapid chargers only used in exceptional circumstances.
Forget Full Recharge Time, Range Added Per Hour or Per Minute is what matters.
A common question is: “How long for a full charge?”, when a far better question would be “how long to provide enough charge to drive 400 kms (or 250 miles)?
Of course a car with a bigger battery may take longer to recharge, but will typically charging for the same time will provide enough charge to drive further than a full charge from a similar the car with a smaller battery.
Now there are vehicles like the Lucid Air with 800km range and vehicles such the Aptera being released with even up to 1,600km range. Of course there are also still EVs with very little range, and it makes no sense to compare time from empty to full of a vehicle with 1,600km of range to that recharge time of a vehicle with just over 100km of range. So don’t be do too focused only on time for a full charge.
What does matter, is how long it takes to add a given amount of range. This can be stated as ‘range per hour’ for slow charging, because when ‘charging while sleeping’, it is easier to think in hours, but for rapid charging, it is better to think in ‘minutes per 100 km’. In practice, there are two measures:
- Range per night or per hour, for ‘charging while sleeping’.
- Range per minute, for the road trip style high speed ‘rapid charging’.
Consider which would you rather have?
- A car with a small battery and a range of only 100km (60 miles), that fully charges in just 20 minutes, but have low range.
- A car with a large battery and a range of 800km that fully charges in 30 minutes, but will travel 400km from 10 or even 15 minutes of charging.
Surely option 2 is the better car to have, even though a full charge does take longer. As battery capacities continue to increase, the time for a full charge from ’empty’ to ‘full’ will become relevant even less often. What really matters, is how much range can be added in a given period of time, or how long will be needed to add the range required.
Charging until fully charged is not that useful anyway.
The goal is always charging to have enough range to comfortably reach the next planned or convenient recharging point. Then, it your going to stop anyway, recharge while stopped unless it is expensive.
All early EVs had so little range it made little sense to do anything but a full rechange, which is why “full recharge time” was at one time useful information.
While with ICE vehicles, it usually makes sense to use most of the fuel in the tank, and then ‘fill the tank’, this is not the normal pattern for every day use of an EV. However, with EVs, there are benefits to NOT fully charging:
- When the battery is fully charged, regenerative braking is often limited, leading to increased wear on the brakes, and less economical driving until the battery has “room” for more energy.
- The final 10-20% of charging, from 80% or 90% until 100% depending on the battery, take be far slower charging, and can even take longer than from 20% to 80% does on some cars. Waiting for that slowest part of charging is best one endured only if that last bit of range is really needed.
- Continually keeping current chemistry batteries fully charger well documented to shorten battery life, and most cars have an option to allow regular charging to stop at around 10% less then fully charged. for this reason.
Picture yourself, 100km from you destination and needing sufficient charge to complete your journey. Would you think “I have a large battery that provides 800km range, so I must fill it and I wish I had a smaller battery that only provides 300km range!”.
Even on a road trip, when using ‘rapid’ charging, you need enough only charge to comfortably get to your next charge. Waiting until reaching 100% is usually wasting time if 80% would provide ample range to comfortably reach the next charging point, as beyond 80%, charging speeds will start to slow down.
Don’t wait until running low on charge.
With ICE vehicles, the trigger to refuel is most often the fuel gauge, or fuel level. While the level changes from person to persons, most people normally fill or plan to fill when the gauge reaches a certain level. This is in large part due to the fact that refuelling is a dedicated gasoline stations or petrol stations. The process of refuelling may be fast, but the overall process takes time and has several steps. Which is in part whey most people fill the vehicle whenever they are going through all the steps.
With EVs, charging can be when parked at home, when at parked at the mall, or potentially, anytime when parked. In some of these locations, charging is even free! With all these places to charge where you were going to park anyway, why not charge every time the price is right. Even though the charging time itself takes longer, if the car is in the right place anyway, charge up!
Even on a road trip, given stops are generally recommended every 2 hrs, a stop will normally be before a recharge is essential, but provided there is a suitable place to have the stop while charging, this means all that is required is to replace the energy used in those last two hours. If, for example than means 200km to 260 km of range (120 miles to 150 miles) to be replaced, the charge time could be under 5 minutes, and still less than 20 minutes even with a relatively slow charging car.
Even if the vehicle does not need charging, connecting to charge can make sense for vehicle to grid or home, providing battery backup power. Further, if wireless charging (see below) becomes common, connecting up may become automatic.
In any event, the mentality of waiting until energy is slow before refuelling, as is normal with internal combustion engine vehicles, should be abandoned for the best experience with EVs. Plug in whenever the power is handy.
EVs Redefine ‘Road Trip Ready’.
There are two experiences of using a car to get people from a to b:
The links above provide further explanation, but think fetching groceries from the local supermarket as clearly a local trip, and a weekend getaway is usually clearly a road trip. Often the lines get can be blurred. What about a rare visit to a special farmers market 3 hours away? Or a weekend getaway in a location just 2 hours away? But generally it is common to have this idea of some trips that requiring more from the vehicle that others.
The difference between the types mean vehicles can need different preparation. In fact, some vehicles are only suitable for ‘local’ trips. A vehicle can be still suitable for ‘local trips’, even though some of following limit use for ‘road trips’:
- Questionable handling or safety: “I wouldn’t want to be driving that on the highway!”.
- The tyres may need to replaced or suspension checked a car tackles a road trip.
- If a service is due soon, it should happen before a lengthy road trip!
The point is, what is required of a vehicle changes between local trips and road trips. With an EV, the recharging changes too. With an internal combustion vehicle, the refuelling process stays exactly the same, even though the refuelling stops can feel different, as they are usually also driver breaks as well.
For local trips, charging is all about AC charging at home, maybe even having home solar, and having best power prices at home. It can also be about top up charging at shopping malls, and needing an type 2 charging cable.
For road trips, charging requires rapid DC charging and the use of a charging network. This can require membership to the charging networks, and typically cost more for electricity as the charging networks are an extra business in the chain, typically not earing income from recharging for local trips. Further, road trips with an EV usually involve working with software such as plugshare, or a better route planner, or an equivalent, or at the very least the cars own route planning software, in order to best plan stops.
The very first electric cars were totally unsuitable for road trips, and there are still some EVs that are unsuitable. Some EVs now are in some ways more capable of road trips than ICEV ever were, but road trip capability requires additional features.
A trip requiring recharging while on the trip, becomes clearly a ‘road trip’, that is different in nature from local trips EV.
Rethink Step: A reverse Perspective.
One way to picture how different an owning an electric vehicles would be is to consider what it would belike coming from an electric vehicle to an internal combustion car.
An EV owner has provide an answer in an insightful article looking from the other side. What would be required as a rethink for a person accustom to electric vehicles, replacing their an electric vehicle with a gasoline/petrol vehicle?
- I have heard that petrol cars can not refuel at home while you sleep? How often do you have to refill elsewhere? Is this several times a year? Will there be a solution for refuelling at home?
- Which parts will I need service on and how often? The car salesman mentioned a box with gears in it. What is this and will I receive a warning with an indicator when I need to change gear?
- Can I accelerate and brake with one pedal as I do today with my electric car?
- Do I get fuel back when I slow down or drive downhill? I assume so, but need to ask to be sure.
- The car I test drove seemed to have a delay from the time I pressed the accelerator pedal until it began to accelerate. Is that normal in petrol cars?
- We currently pay about 1.2p per mile to drive our electric car. I have heard that petrol can cost up to 10 times as much so I reckon we will lose some money in the beginning. We drive about 20,000 miles a year. Let’s hope more people will start using petrol so prices go down.
- Is it true that petrol is flammable? Should I empty the tank and store the petrol somewhere else while the car is in the garage?
- Is there an automatic system to prevent gasoline from catching fire or exploding in an accident. What does this cost?
- I understand that the main ingredient in petrol is oil. Is it true that the extraction and refining of oil causes environmental problems as well as conflicts and major wars that over the last 100 years have cost millions of lives? Is there a solution to these problems?
For this page, #1 is the most relevant, and conveys the important concept that “recharging while sleeping” is the normal, and going to a charging station should be an exception that only happens a few times a year.
EV Charging Equipment.
Two Types of Charging Equipment: AC for Home/Urban Vs DC Road Trip Charging.
Fuel consumption data is divided into ‘urban cycle’, and ‘highway cycle’ because there are two different types of driving. With fossil fuel vehicles, the refuelling is not very different for these two driving types, but with EVs, the recharging is very different. When it comes to the practical side, the two separate sections here one ‘home’ and road trip’ charging are the most relevant, but background reference information is in this ‘combined’ section.
- local trips on the urban cycle: charging is just in the background while you do something else.
- road trips on the highway cycle: charging needs to be fast, as otherwise you will be waiting.
The Three Charging Levels, and the equipment.
Why 3 levels of charging? An now even 4 “charging modes” (the IEC 61851 Standard).
It may feel like a new world where there is more than one way to refuel, but in practice, even with gasoline vehicles, refuelling on a long trip is different as it is often combined with a rest stop, perhaps with some food or fast food, and has a different feel than filling up during a normal week while commuting.
Refuelling an internal combustion engine vehicle is not necessarily convenient, but it is always fast, and when refuelling it is the main thing you are doing at that moment. Recharging can happen while you do something else, and at places you did arrive at for the purpose of recharging. At home while you sleep, at the mall while you shop, or at a restaurant while you dine. Recharging can be in the background while you do something else.
Recharging an electric car, you should avoid ‘fast’ most of the time, as rapid recharging is more expensive, less convenient, and should only occur on road trips or in exceptional circumstances. The trap is, rapid recharge feels most like the familiar refuelling of an internal combustion engine, so it can feel like it should offer the familiar. However, for electric cars, recharging at home is more convenient than the familiar refuelling, and rapid charging is slower than the familiar refuelling. An EV that is only ever rapid recharged is a worse experience than an ICE vehicle, and when an EV owner recharges while sleeping the EV experience is an improved experience. The best EV experience requires using the most appropriate charging level for the occasion.
There are several articles on the charging levels already available, but such articles are often a little misleading, as they are often sponsored by people selling home chargers with a motive to upsell chargers.
Initially, with early EVs, a faster way of charging than a standard power point was introduced, giving rise to two “levels” of charging. Then, fast DC charging was introduced, providing a third “level”, even though it was never officially labelled a third level. Then the IEC 61851 standard was introduced, defining 4 modes, with level 1 split into the bad way (mode 1) and the good way (mode 2). Level 2 and DC charing became mode 3 and 4 respectively, and and more clearly defined.
It is important to consider that wireless charging is real, just becoming available, and will become more important over time. Wireless charging is perhaps a fourth level, or 5th mode?
Level 1 the bad way (Mode 1): Banned in most countries.
This is simply directly connecting the domestic wall socket to the AC pins on the charging socket of the car.
There are two problems here:
- There is no information to the car on how much power is safely available.
- The entire power cable, much of which will be on the ground next to the car, will be ‘live’ unless the whole time the car remains connected, unless someone manually switches off the power when charging is complete.
Most developed countries do not allow this system, and cars are configured to no charge unless the supply can send control signals and identify there is a controller somewhere.
Level 1 Charging (Mode 2), Mains power: Solution for charging in the background while sleeping.
Level 1 / Mode 2 charging, is still charging a car from a standard home mains power socket, but adds an intelligent controller box inline in the cable, which makes a safer solution.
For most people, this is all you need when charging at home.
Level 1 / Mode 2 charging will typically add around 4 to 7 miles per hour of range using USA/Canada/Mexico/Japan style 120v power, or 8 to 15 km per hour (5 to 10 miles per hour) in the rest of the world where mains power is 240v.
How fast ? It depends on the national power. All cars can support the fastest possible level 1 charging:
- 1.8 kW in the North America, Japan and other 110v-120v countries.
- 2.4 kW from 10A sockets outside North America and Japan
- 3.6 kW for 15A sockets outside North America and Japan
Level 1 is for home charging in the background while you are at home. It is not very useful for background charging while at places you spend less time, such as the mall or a restaurant, or even the office. And it nothing beyond an emergency solution when on road trips, as during a road trip you are normally away from home. Home charging is about ‘recharging while sleeping’ after a typical day driving. Most people only need to be able to add less than 80km or 50 miles of range each night.
There is myth that charging from standard mains socket is too slow to be useful, while for most people it is sufficient. See this quote from ‘fully charged‘:
For the occasional long-distance electric car journey, now I say occasional because most people don’t drive 350 miles in a day, regardless of how many times I get told that on twitter, statistically, it’s inaccurate. Its about 25-30 miles a day is the average car journey, not only in the UK but in every European country and North America. In North America that is the average and yet you could drive 3,000 miles across the United States, which people have done, and people do regularly, but not that often.Robert Llewellyn from Fully Charged.
While a full charge from empty using level 1 could take over one full day, how often will you arrive home with an empty battery, and also require a fully charged battery again the next day? As discussed in the section on home charging below, for most people such a situation would happen so rarely, that visiting a rapid charging station first rather than arriving home empty on those rare occasions would not be a problem.
This means Level 1 charging from a standard mains socket is sufficient for most people, most of the time for home charging, provided they leave their car connected and can charge while sleeping. However, those owning an inefficient vehicle with a long commute in a 110v country, or those sharing the charging point between several vehicles, the next step may be required.
Use of level 1/Mode 2 charging beyond charging at home, is best considered only as a fallback for when nothing else is available.
Level 2 (Mode 3): Faster charging, but still in the background while doing something else.
If you take the control box that was in the cable with level 1 / Mode 2 cable, and mount it on the wall, or in its own stand alone cabinet, then your almost have Level 2 / Mode 3 charging.
Only almost, because there are a couple of additional steps, that allow having the power of several household power points available from one single unit: upgraded wiring and extra protection circuits.
Being equivalent to several household power points is the step up from the previous level 1 / mode 2 where charging has only the power of a single home power point. This also makes using this mode of charging in the background while at at work, or the mall or supermarket or dining, at other locations. Plus, the ability to provide a full charge from empty overnight, makes this mode very useful for an overnight stay during a road trip.
How much faster is level 2? It varies. The speed limited by charging technology within the car.
- All cars can support at least 7kW (around 3x level 1)
- Most cars including Teslas and similar priced cars, support 12kW (around 6x level 1).
- European luxury cars outside of North America, Japan etc, cans support 22kW. (10x level 1)
Some ‘wall box’ units can be plugged in, typically to a specialised high power socket with more power than regular home sockets. In the US or 120v countries, such sockets may be available for laundry appliances, and in 240v countries, 3 phase power sockets may be used. However, wiring the unit directly to the power source and avoiding any socket is best.
Box wall boxes and freestanding units are ideally directly connected to main power without any plug and socket between them and the point of supply, as this eliminates any constraints of such sockets, and allows for the higher power rating.
Level 2 / Mode 3 charging provides for high speed AC mains power charging, from either a wall mounted unit, or free standing supply equipment unit, and incorporates either a built in charging cable, or one of the EV specific AC charging sockets, as listed here, such as CCS1 or CCS2.
Wall box units are typically for home use, while applications for stand alone units range from company car parks, shopping malls and super markets, to charging at overnight accommodation or other public venues.
For home charging, stepping up to Level 2 / Mode 3 can offer more convenient charging, faster charging, or both.
Generally, level 2 charging is most appropriate for charging in the background while you do are doing something else. You don’t normally visit to a level 2 charger to get charge, instead you visit that location for another reason, and use the charger while your are there.
Outside the home, main locations that may offer Level 2 charging include:
- Shopping malls.
- Office carparks.
- Commercial carparks.
- Overnight accommodation.
- Hotels and event venues.
- Depots for delivery vehicles.
While Level 1 charging can charge overnight after a ‘normal days’ driving, Level 2 charging provides for fully charging vehicles such as travellers that may arrive with an empty battery, and need a full charge for tomorrows drive.
In general level 2 charging will normally be focused on provide a useful amount of charge, in the time period visitors will be at the venue.
Level 2 car charging can be limited to 7kw, 12kw or sometimes as high as 22kW or even 40kW.
Level 2 chargers also have different capabilities, and often are more often only 7kW in 100v countries, and up to 22kW in 240v three phase countries.
For home charging Level 2 / Mode 3 charges may be used even for providing similar power levels to Level 1 charging, because a wall box is tidier than an inline control box, and can provide convenient access and storage for charging cable.
This site quotes range distance added per hour as: 3.7kW= 20km, 7kW=40km and 22kW=120km, which should be indicative.
Level “3”(mode 4)/DC: Rapid Charge for road trips, and emulation of gas/petrol/diesel refuelling.
Though not officially called Level 3, the next level of charging is ‘DC rapid charging’, and is the system specifically designed for charging electric vehicles. While Level 1 and 2 are designed around sending the AC power that already exists in national electric grids through to a car, DC charging is all about the provision of electric power supply equipment designed for the needs of charging electric vehicles.
Rapid charging is needed when ‘charging while sleeping’ isn’t practical. Ideally, EVs would have sufficient range to deliver what ever is required even if driving all day, and thus always able to be charged after the day is over. Reality is, there will always be times when a way extending a vehicles range is required, although in future this may be through road based wireless charging.
The goal of rapid charging is the highest possible transfer of power possible into the vehicle, and this means the greatest stress on all electrical systems. Rapid charging should not be needed often, but when it is needed, you tend to want it as fast as possible.
Charging quickly requires high voltages and currents. Normally in homes, there is high voltage mains AC, and plug packs produce low voltage DC. AC is a great way to send power over long distances, but less and less equipment directly uses AC. Most equipment now first converts AC power into DC, and cars are no exception. All batteries, including EV batteries are always DC, and are always charged with DC power.
The DC power used to charge EVs, is charging using hundreds of volts, supplied at the exact appropriate voltage required at and given time, and this type of power is only available at high speed chargers. This DC is nothing like the lower voltage DC associated with batteries in flashlights at home!
Charging an EV battery, requires applying the optimum high voltage DC power battery for the current state of charge of the battery. There are two ways cars source the exact voltage needed at each point during charging:
- The cars’ own internal DC voltage generator, which can convert a range of AC voltages into the DV voltage as required during charging.
- External high voltage DC supply equipment, that will supply the exact DC voltage the car determines it requires at any time.
This means cars can flexibly charge from domestic AC power to provide charging withing the power limits of their internal circuitry. These circuits can handle beyond the maximum possible from normal household sockets, and can handle typically power from special high power outlets, of up to either 7, 11 or 22kW depending on the vehicle.
AC power is normally the lowest cost source of charging current, and therefore is the preferred solution when there is plenty of time to charge, such as at home over night.
When faster charging is needed, specialised DC power supply equipment is the solution.
As a general guide:
- AC: charging at home or lower speed charging, or charging smaller batteries such as those of PHEV.
- DC: Newer, specialist rapid charging currently capable of delivering 350 kw.
The Change: From Gas/Petrol/Diesel Refuelling vs EV Charging.
What the? Different Types of Refuelling/Recharging?
The only place you can refuel a petrol or diesel vehicle, is at a ‘gas station’ (or ‘petrol station’ for those outside the US). A specialist location for refuelling. The entire gas station is the equipment for refuelling.
Having made a trip to a gas station, financial constraints aside, you may as well fill the tank as it will make little difference as the visit will take almost the same time to fill the tank or half fill the tank, unless the vehicle is very large.
|Internal Combustion Engine Vehicle (ICE)||Electric Vehicle (EV)|
|Road Trip Important Specification||Distance Between Refuelling||Time To Add Range at Fast Charger|
|Normal Use Important Specification||Days Between Refuelling||Ranged Added Overnight|
|How To Refuel/Recharge||Special Stop at gas station||Normally just park at home.|
On Road trips at charging station.
A Surprisingly Very Different Experience.
Before concluding what range is needed to end range anxiety with EVs, it is worth considering the role refuelling plays the range we need.
Part of the reason our current vehicles need the range we are now expect, is that refuelling with gasoline or diesel, is not something we want to do every day. Most of us do not refuel until less the tank is less than half full.
In normal day to day living, the range of our vehicle determines how often we have to refuel. Refuelling takes time out of our day. There can be queues and we can do nothing else while we refuel. Fuel is also dangerous, and has fumes that are also dangerous, and this determines the character of the refuelling point, and why we are required to pay attention to what we are doing.
The National Fire Protection Association requires that they’re put up as a precaution. Phones do cause static electricity and just because it hasn’t happened yet, that doesn’t mean it never could. Their rules also state that you’re not allowed to use electronic materials at gas pumps, and cell phones fall into that category. The NFPA advises that you always follow all rules posted at gas stations and consult your phone’s owner manual for information on proper use.Why You Need to Stop Using Your Phone When Pumping Gas
The primary reason you shouldn’t use your phone at the pump (besides the fact that there are signs telling you not to) is that it’s a major distraction.
Now consider electric refuelling. All that is required is a power point. Refuelling can be at the office, at home, or even at the supermarket. You don’t need to pay attention, and you won’t toxic chemicals on your hands or clothes. The worst way to refuel an electric vehicle, is to follow the old behaviour, and go to a location specifically to refuel and have nothing else to do while refuelling. Refuelling EVs can be no more inconvenient then using the right parking space, and is definitely best not done in the old way, as a special place just for refuelling.
This really impacts needed for those who can charge at home or the office. A change in thinking from “I refuel when the time comes” to “whenever I park here I ‘connect’ the car”. Then, every day their vehicle has the full range, in place of a potentially half empty tank, where the half already consumed has saved the driver the need to refuel during the past few days.
In normal use, a major role of the ‘range’ of a gasoline/petrol or diesel vehicle, is saving you from having to refuel everyday. That aspect of ‘range’ no longer applies to anyone with some form of permanent, or electrified parking space.
Australian Input To An Answer “Can I Charge In Remote Locations?”.
Consider the following:
- Australia is the least densely populated country amongst populous countries, with 3 people per sq km2.
- A higher percentage of Australians live in urban areas than with other large counties, making the non-urban areas even more sparely populated.
- Australia has one of the lowest rates of EV adoption of any developed country. (2.4% compared to 4% for USA., 5.5% for NZ, 18.3% for France etc at the time of this update in 2022).
The combination of these factors means is the distances between charging infrastructure will be quite extreme, and that if a range is adequate for an EV in Australia, that range is going to workable in any country. But then, Alaska for example, at 1.3 per sq mile or 0.5 per km2, has a lower population density than the Australian average. So, take it further, take the “state” of Australia, (or technically “territory) of the Northern Territory, with a population density of 0.16 people per sq km2, and at the time of this report, and only 61 registered EVs in total, being only 0.03% of vehicles.
Even in the Northern Territory, the report is that a P100 Tesla Model X, normally charged only to 90%, has fully adequate range for driving without problems in the Northern Territory.
Peace of mind for Mr Smith and his family comes from knowing that his vehicle charges overnight at his home, “just like a mobile phone”, powered from solar power collected during the day, and that — when he leaves in the morning for work or to drop off the children at sport — his car is ready to go.ABC, Dec 2021: Sales of electric vehicles expected to surge in the NT in 2022
“I often hear people say that you can’t drive an electric vehicle in the NT, and I use that opportunity to let them know that it’s pretty easy actually … I let them know some of the things that I’ve done,” says Mr Smith, who is from Darwin.
Driving the Tesla, Mr Smith circumnavigated Australia over 18 days, often exceeding 1,000 km in a single day.
“I did Port Augusta to Melbourne in a day, well over 1,000 km, and Sydney to Brisbane in a day,” he says.
Mr Smith has also travelled extensively in the Northern Territory, including doing the Alice Springs-to-Darwin drive many times.
“It would be right to say that better and faster infrastructure along the Stuart Highway would make the journey easier, but there are many more electrical outlets in Australia than petrol stations, so in terms of being able to charge your vehicle there’s no problem,” he says.ABC, Dec 2021: Sales of electric vehicles expected to surge in the NT in 2022
What is not revealed is how many minutes per 1,000 kms are required for the recharging, but the implication is that charging is not always fast, but can be found almost anywhere.
‘Home’ Recharging: Charge for ‘Local’/’Urban’ Transport.
What is home charging?
Home (or at work) Charging is at least 95% of all EV charging.
For most people, home charging is literally, charging while at home. Then there are those who park an charge there car at a regular location while at work. In general, home charging is charging in a location with charging, where the vehicle would normally be parked long enough to charge while packed, during a normal week when the driver is based at home.
Another way to think of it, is home charging is the charging done in places the car would regularly be parked anyway.
Even this report on charging habits in the US, surveying only vehicles with very limited range (like older Nissan Leafs), found 98% of charging events were performed at home and work on work days.
For most electric car owners, “charging while sleeping” is so normal, that there may be months and months between visits to public charging station. Visits to a public charging station can require less attention than refuelling in ICE vehicle, and can happen at a place you may already visit, but even the best public charging experience is less relaxed than just plugging when parking in at home.
Just plug in when you get home, and unplug next morning, or before leaving. It doesn’t matter that you did not need to be plugged in the entire time. In fact, with wireless home charging, there are already some cars where you do not have to do anything, and charging just happens while your are parked.
Home Charging Replaces Periodic Visits to gas stations.
With an ICE vehicle, around once or week or so for most people, a stop off for a refuel is required. These refuel stops are more mundane that the refuel stops on a road trip, and almost never involve a bathroom break or a meal. Some people sometimes grab a quick snack or emergency groceries. It is most common to fill the tank. While it is not universal to fill the tank, the visit was for the purpose of getting fuel, so unless the price is high at the time, or there is another issue, it is normal to keep filling until the tank is full.
Charing at home is a very different mentality. Unlike the gas station, charging is not the reason you are at home, but rather, is something that can happen in the background while you are at home. With adequate home charging, the car will normally be fully charged every morning. In fact normally, much the the time the car is connected at home, it will just be connected and not charging at that time. It may be waiting until later to charge when electricity prices are lower, or have already finished charging. The car may also be plugged in in order to allow the car to provide backup power plugged in the event of a blackout.
If you have home charging, then charging is something that happens in the background while you are at home.
While some people find Level 2/Mode 3 home charging preferable, or even needed, most private cars spend sufficient time at home that even Level 1/Mode 2 charging will ensure that other than when on road trips, there is no need for charging elsewhere.
Home Charging Typically Only Needs To Add 60 km or 37 miles Of Range Per Day.
The average US motorist travels 13,500 miles or 22,000km which, divided by 365 gives an average of 37 miles or 60 km per day. In reality, those miles by average US motorist will normally include some long mileage road trip days, where there will need to be charging away from home, and the average distance travelled when at home will be a little lower. This makes the 60km (37 miles) an over estimate, and for those outside the US where annual distance driven are normally lower, a significant over estimate.
But using the 60km/37 miles number as an average, if you can add 37 miles or 60 km each day range by charging at home, then you would never need to charge elsewhere, other than on “road trips days”, when you may travel further than the vehicle full range, and will need to charge away from home anyway. For a car with 250 miles or 400km of range, a road trip day may mean a day with around 4 or more hours of just driving, which is not a normal day at home for most people.
All of this means that most people can do all their charging at home, “recharging while sleeping”, with the exception of vacations other other long road trips.
Determining Charge Equipment for Home Charging.
Ability to fully charge every night is overkill, unless you drive the full vehicle range every day.
Yes, home charging capable of fully charging a Lucid Air with 800 km (500 miles) of range in a few hours is readily available, and if you can afford a Lucid Air, then why not just buy that capability?
However, that rate of charge to fully charge a Lucid, which would be needed by people who drive 800km x 365= 292,000 kms or 182,000 miles) every year, may be a complete waste for most people. For others is may not be feasible with the power available to them. Plus, with wireless charging, and vehicle to grid charging, both on the horizon and requiring a new charging equipment, it may make little sense to spend a lot of money on charging that will never be needed in the interim.
Rather than overkill, it can make sense to know what you need.
Almost 2021 models EVs have a range of at least 350km of urban range, which means only needing a full charge overnight at home only on occasions you need to drive around 300km on each of two consecutive days. That is, arrive home having used the full range one day, and need a full recharge to again be able to have full range the next day. Given that average of 60km per day most of us drive, two consecutive days of driving 300km are rare, and two consecutive days with that number hours driving almost always involves staying somewhere other than home at least one night, and needing to charge at a charging station anyway. When on a road trip you typically do need fast charging, but a fast charger back home will not help.
Calculating what is a typical driving day when based at home.
But what recharging do you need? Enough recharge after a typical “driving day” when based at home.
On formulae is to divide annual distance travelled by 52 to get weekly distance travelled. While there will be exceptional weeks, mostly likely such weeks include road trips, when some charging away from home will be needed anyway, so this will usually give a good picture of the requirement to charge at home per week.
Some days of the week may lower the weekly total as they are not “driving days”. The goal is to look at the typical for “driving days”, when still based at home which days are the main driving days? Are the main driving days week days, so divide by 5 for distance per day, or driving days mostly only on weekends, so many divide by 3 on the basis all the weekdays in total are just like one extra weekend driving day? Just dividing by 7 is normally going to make the distance per driving day to low, so divide by 6 or less depending on how uneven your days are. Again, it is only home based driving days, not days spend all day driving, when road trip charging will be required anyway.
Step 2: Calculating Charging rate required from typical home based “driving day”.
Having calculated what distance is travelled on a typical driving day, the next step is to consider what charge, or “energy” is required.
From ev-database.org, a Tesla model 3 has a real world consumption of 151 Wh/km, while the Jaguar iPace has a real world consumption of 223 Wh/km. This means to recharge after travelling 60km (37 miles, the Tesla requires 9kWh, and the Jaguar 13.5 kWh. At US home power levels of 1.8kW, the Tesla would recharge in 5 hours, and the Jaguar in 7.5 hours.
Having the charge required for the typical driving day allows calculating how many hours will be required with the different charging rate solutions available in your area, and, ideally, checking that solutions available have not only enough time to provide the required charge, but more than enough time.
Exceeding the typical driving day on consecutive days.
That 60km (37 miles) is an over estimate of the typical US day, but not necessarily of the typical US “driving day”. Plus even the figure for “driving days” there will be days beyond typical. So, for example, the Jaguar which needed 7.5 hours to recharge after a 60km day, only had 7.5 hours available to charge, any day above average, would mean the Jaguar would start the next day, less than fully charged. After a days of 120km (74 miles) per day, and only charged at 1.8kW for 7.5 hours, the Jaguar would have 13.5kWh less than the day before. 5 consecutive days of this double distance driving, and the Jaguar would have lost 2/3 of it battery capacity, and make visiting a fast charger well advised. But it could manage a working week. If the next two days were at home, it would return to full change just by staying home. The point is that it takes several days of exceeding the typical before an extra charge is needed, and even if one needed occasionally, it need not be a big problem.
Cable or wall-box: Level 1/Mode 2 Cable vs Level 2/Mode 3 wall-box.
Most people looking to charge just one EV will find that even a cable with the control box inline will provide all the charging they need. If so, and mounting a control box on the wall is problematic, then the cable with a control box is the solution. Note, the control box will/should be close to the power socket, so should be out of the way, but the cable from the control box may be on the ground.
If mounting a control box on the wall is no problem, then check pricing. Sometimes lower rated wall boxes cost very little above cables with inline boxes, and may be a more asthetic solution.
Also most wall mounted units can be set a slow charge if desired.
there may be a box with built in cable that is costs very little extra.
From the calculations above, it becomes clear that most people do need a wall box that can charge beyond
You can buy home charging stations for most electric vehicles, even though in practice, for most situations, charging from a regular electric socket should be all you would even need at home, particularly outside of Japan or North America as in most countries the regular voltage is 240v.
The main benefit from a fast home charger that is allows only every bothering to plug in every 3rd or 4th day, or in many cases, perhaps once per week instead of every night. Why not charge a little every night? Perhaps the ‘home’ in question a second home, or there is one place for charging shared between several cars?
It could be that for some people, it is too hard to change a mindset that ‘refuelling’ is best left until ‘the tank is getting empty’, so to plugin in every time they are home, even if the battery is quite full, means breaking a pattern established over years and years.
While the provision for fast charging is essential to electric vehicles on road trips, it is not critical for charging at home.
Home Charing Times From “granny cable” Level 1 / Type 2 cables or equivalent.
The cables with an inline control box, as used with Level 1 / type 2 charging, are also known as “granny cables”.
Despite the negative name, these cables, or wall boxes set to the same current limit, can provide all the charging most people need.
Note that US, Canada/Mexico and Japan and have 120v power at home, while almost all other countries have 220-240v. Confusingly, US/Canada/Japan can also have high current 240v sockets in laundries or other locations, but this North America style 240v is from ‘spit-phase’ high current sockets, and very different from single phase 240v in other countries. USA split phase 240v typically provides more current than the single phase 20-240v of Europe, China, Australia, Africa, etc.
240v data here is not North American style split phase 240v.
Charging at home data (12 hours ‘overnight’ figures where possible). Note actual owner experiences tend to give high range overnight than web sites of wall box resellers, or web sites using data from wall box resellers.
- BYD Atto 3 / Yuan Plus (7kW capable)
- 220-240 volts, using supplied 8A cable: 150 km overnight.
- Tesla Model 3 (11 kW capable)
- Tesla Model S (11 kW capable)
- Jaguar i-Pace
- 240v: 11km/h or 132km/ overnight
I may add more examples to this table over time.
Problem: No Home Charging? Upgrades, Street Chargers, Or Solar A Solution?
Many People Have No ‘Home’ Charging: Only On Street Parking, Or No Power Socket.
Statistics on what percentage of people have parking with access to a mains socket, will vary not just from country to country, from locality to locality, and even within a town or city, area within that town or city. I found specifications for the UK that state that 25% of all vehicles in Britain are parked on the street when at home. However, even some vehicles with off-street parking, do not have access to electricity in their allocated space. For example, for apartment complexes, providing mains electric car power in each allocated space or garage, would require the addiction of significant extra infrastructure to facilitate measuring the power usage at each allocated space, which is most often not currently in place.
Some homes have little or no off street spaces, and some families have more cars than spaces.
This division between those with access to a power socket for home charging, and those without, could be the great divide of the electric vehicle experience. This is not a question of access to rapid charging at home, as most people, particularly in built up areas, can achieve most of the charging they need from a regular mains socket. Even for those this is not a perfect solution, a combination of mains socket charging with occasional use of rapid charging is far far better than no home charging at all.
Right Now, Think Twice Before Buying If You Can’t Charge At Home.
There are so many great home charging options, and even standard wall socket will satisfy most needs, and matching that experience for the as many as around 50% of all people without access to a power point where parked when at home is a real challenge. Some will have suitable charging at work, but otherwise, at this time, for these people owning an EV is going to be far from the experience it should be. The best experience requires charging from home. Without charging at home:
- Electricity costs more as recharging stations are resellers of electricity, increasing car running costs.
- There is the added inconvenience of needing to find time to go to recharging stations.
- Battery life with most batteries is reduced by rapid charges and the deeper cycles that go with rapid charging.
For a move to electric cars across society, this problem requires serious attention. Society has had 100 years to adopt and evolve around fossil fuel cars, some evolution is now required around electric vehicles. This is the key evolution required.
There are shopping centres with charging spaces for EVs, and some people can charge at their place of work, but these are not universal solutions, and while the lure of often free charging is a lure for customers right now, it is hard to see this as part of wide scale solution.
However, there are solutions coming. The two main reasons for not being able to charge at home are:
- Home parking is in an underground carpark, without available power for charging, as often is the case with apartments.
- On street parking is the only available parking at home.
Problem number 1 should be resolved as more people have the need and as upgrading underground parking is practical once enough people need it. The biggest problem here is that charging networks trying to offer
Charging Solutions For On Street Parking.
But for problem number 2, on street parking, solutions are more complex. There are many proposals, such as such as the one in the video to the right, with posts that can be housed at the street side, as well as other solutions that convert street lamps into charging posts.
While there are proposals for on street parking with power, who funds such infrastructure is complex issue, and normally assumes those charging on street will be paying a premium for electricity compared to those charging at home in order to fund the scheme operator.
‘Electrifying’ the street can work in densely populated areas, particularly with wireless charging, but there is a risk that the electricity will come at a premium to help fund the infrastructure. Even when paying a premium for electricity, EVs are still less expensive to operate than ICE vehicles, but it would be better if everyone had price parity. Society regards electricity to the home as an essential service, and with EVs, electricity to the car parking location may need similar consideration.
There is a social question to be answered.
Solar: A solution For Cars Parked Outside?
Unlike the solar challenge races, a regular car cannot travel 1,000km (600 miles) on the solar energy collected in just one day, but adding up to 60km of range for each day is possible, and given the average distance driven per by vehicles, then that may just be enough to keep the battery sufficiently charged most of the time for most people.
There are soon to be released cars:
- Sono Scion, with around 50km of range per day from solar alone.
- The Lightyear one with 38-60km of range per day and the
- Aptera with around 65km of range per day.
Tesla even has solar charging plans for their Cybertruck. It is all very promising, and all are taking orders, but Tesla has nothing is in mass productions at time of writing.
More articles on solar vehicles:
Solar Car Covers & Blankets and Accessories.
The blanket of solar cells is potential solution for travel to remote locations, or those with a private place for parking that has no access to power.
The solar car cover is a potential solution for people who park on the street, with limited distances travelled during their normal week. The current 105 km week of range quoted in the article above does equate to only just over 5,000 km (3,100 miles) per year, but this is excluding road trips, when rapid chargers would be required anyway. The company hopes to triple the range per day, which would then be sufficient for the “urban” part to their life for most vehicles, but even at the current power generation level it would be a solution for many people.
The Tesla Cybertruck will have a solar “bed” option that will add 15 miles (24 km) per day according to Elon Musk.
Off Grid Solar Vehicles.
Another type of charging is charging when parked at a remote location. This is most relevant for vehicles that may spend long period of time at a remote location such as campers.
A proof of concept vehicle has already been able to gain 130km (80 miles) of range per day. All of this additional range is completely without cost of carbon footprint.
There are also a umber of camping conversions and camping trailers that propose using solar power for not just camping, but also to charge the vehicle.
Designation Charging: Background Recharging Away From Home.
Destination charging is “charging while your are there” at a location you were going to visit even if you were not charging. Some locations provide chargers, allowing patrons to “charge while visiting”, either at commercial rates, or even for free, as a way to help attract patrons.
Tesla even provides a list of “destination chargers” around the globe.
Road Trip Rapid DC Recharging: Emulating a ‘gas station’ refuel.
Making Sense of DC Charing Specifications.
What specifications rarely say, but actually matters.
Road trip recharging is when you need to stop to charge enroute, because otherwise, you would run out of charge.
Unlike home or background charging, every minute spent DC rapid charging can add to the time it takes to reach your destination. Of course, people need a break too, so if the recharging can all happen in less time than the people need, great. That consideration, what matters is how long until the car will have enough charge to reach the next logical within that or your road trip.
Car Peak Charge rate: Rarely seen in the real world, and charger dependant.
Cars often have a maximum rapid charge rate, expressed in kW. For example the Mercedes EQA has a maximum charging rate of 100kW.
This number is not very useful, as in practice, it can be more like a guarantee the car will never charge faster than that number. When charging, that maximum charge rate may never even be seen. Plus, when comparing two cars, the car with the lower number may actually charge faster.
As an alternative to maximum charging rate, manufacturers usually give a more helpful number like:
- 10% to 80% charge in 20 minutes.
This information is more useful in that it reveals the speed of charging in a very specific, optimum, set of circumstances. Of course you are unlikely to arrive to charge with exactly 10% of charge, nor finish charging at exactly 80%. However, as well as the conveying the speed between these two levels, this information also conveys that for this car, charging will be fastest between 10% and 80%. For this car, waiting until below 10% or charge to start charging, and above 80% will produce slower charging.
While 10% as a lower level, and 80% as an upper level are fairly typical, different cars will have different lower and upper percentage levels.
The ‘fine print’ is that to achieve the rated charging speed, the battery must be at ideal temperature, and the charger must meet required charging speed.
The specification may even make clear what speed charging station is required. As for the battery temperature, there is a “goldilocks temperature” of not too hot, and not too cold, and some cars will allow for “pre-conditioning” the battery prior to charging, so the battery will be at ideal temperature.
Both peak charge rates and charging stations have power expressed in kW (kilowatts). For an example, a 50kW charge station can provide up to 500 volts at 100 amps.
Do not believe the peak number specification: Calculating real charge rates.
There are two really useful, practical numbers, and they are not usually on the specifications. To compare cars, you need these numbers, or the very least the second number:
The important charge rate numbers:
- Average kW charge rate = (full battery charge x fraction charged) ÷ time in hours.
- Distance added per hour = Average kW charge rate x (range ÷ full battery charge).
Most cars also a rating specifying something like “charges from 20% to 80% in 30 minutes”, “20” in this example is the starting point level of charge, and the “80” is the end point. Still not an ideal number for comparisons itself, but it does give key numbers allow calculating the useful numbers.
For the formulas above, subtracting the smaller percentage from the high number gives the “% charged”, which in this example is 80-20 = 60% charged, or 60/100 charged = 0.6 charged. The battery is 0.6 charged in 30 minutes. 30 minutes = 0.5 hours, so 1.2 charged in 1 hour. If we have a 60 kWh battery, this would mean:
- average kW charge rate = 80 kWh x (0.80-0.20) ÷ 0.5 h = 60 x 0.6 ÷ 0.5 h = 96 kW.
Now assume the car range is 400km.
distanced added per hour = 96 kW x (400 km ÷ 80kWh) = 96 x 5 = 480 km added per hour
So charging for 1/2 hour will give 240 km of range. Note that this still only applies while within that 20-80% band, and will be slower if outside that band.
If you have Tesla that does not reveal full battery charge, then you will be uncertain of average kW charge rate, however you can still calculate range added per hour. Just guess the battery capacity in kWh, and it cancels out in the 2nd formula, so only the average kW charge rate will reflect how bad your guess was.
When to rapid charge: Only when absolutely necessary.
Rapid Charging Is Not Normal Charging and is expensive: Avoid it when possible.
Don’t rapid charge often! There is a reason I moved this section below home charging.
Limit the use of rapid chargers to when necessary. There are 3 limitations to rapid charging:
- The cost per kW will typically be 3x to 4x the cost of home charging.
- You normally need to ‘hang around’ or to be available to move the vehicle when charged, as rapid chargers are usually in demand shared resources.
- There is a risk that too much rapid charging can limit battery life.
If you are using rapid charging on days when you will sleep at home that night, you are probably doing something wrong. For most people, over 95% of EV charging is home charging, and rapid charging is for road trips. Plus, special temporary, deals aside, it is around 4x more expensive.
How often do you go on a ‘road trip’? A ‘road trip’ means either, at least one entire day mostly spent driving, or one or more nights away from home. For most of us, these do not happen that often, but the capacity of a car to do a road trip is very important to us. Like the top speed specification of a Ferrari that doesn’t actually get driven fast often, knowing you can do it if you want is important.
For most people, fast charging is only every used on road trips, but it does matter, and it can be a sensitive issue, as historically EV recharging has been really slow, and it is still not perfect.
So how fast an EV can be charged from almost empty is a specification that gets a lot of attention, but if you end up doing it often, something is wrong.
Generally, for most batteries, rapid charging shortens battery life. While you may rapid charging your phone, the battery is less valuable and cars typically remain in use longer than phones.
Road Trip Rapid Recharging EV or Refuelling ICEV: It is naturally different.
We may not give it much thought, but even with an ICE vehicle, road trip refuelling is usually different than filling up when not on a trip. Travel is most often with a group or the family, and the stop may also be a bathroom stop, and a meal break. There is usually a different feel then fitting in the periodic refill into local trips. With an EV, that difference increases, because this is normally the only time you use a fast charger.
When refuelling an ICE (internal combustion engine) vehicle on a road trip, it is normal to fully fill the tank. Why not fill the tank? It has little impact on the time taken, and it gives more range before the next refuel is needed. We don’t think much about how long it takes to fill the tank with fuel, because unless we drive a huge truck, time difference between fill and partial fill makes little difference. The visit requires turning off the highway, getting to the pump if there is a queue, and the paying can step can take as long or even longer than the filling time. The filling time is just part of the overall stop, and how long the filling takes is not normally that significant. takes to fill the tank.
When recharging an EV (electric vehicle) on a road trip, there are reasons why it is not always best to ‘fill the tank’:
- For some EVs, charging that last few percent is slower, and not worth the extra wait, so it can be best and most time efficient to recharge only to 80 or 90%, depending on the vehicle.
- Recharging can generate heat in the battery, and the longer the recharge, the more heat, so more frequent partial recharges can a avoid a car reducing recharging speed to avoid excess heat.
- Available rechargers may be slow, making a ‘top up’ and then travelling to a faster charger the best solution.
Paying for recharging differs from traditional payment for refuelling. Chargers are all pay at the pump and there is normally no associated cashier. While with traditional refuelling there is normally a staff member somewhere, most often there is no human involved at all with recharging. Modern chargers can communicate with the car, so connecting the charger connects communication with the charging network operator. If there is already an account with the correct options selected, the cost of charging cam be charged to the account of the car owner automatically. Otherwise, paying is often through an ‘app’ on a mobile phone, and there can be lower prices on charging networks if the car owner is a subscriber. It can make sense to become a subscriber for the duration of a road trip. Electricity from the charging network operator can be more expensive than directly from the electricity company as may be the case at home, although charging networks can offer special deals that become bundled with a car purchase.
With an EV, in 2021, a recharge stop should require no more than 20 minutes with newer vehicles, but could take 40 minutes with some models. How long should be allocated for a given recharge can also depend on what there is to do while recharging. Is it time for breakfast, lunch or diner? If you were going to be stopped anyway, even a slower recharger can be time efficient.
If a road trip stops will include trying to feel refreshed and perhaps involves a meal and bathroom stops, then there may be no time penalty as these things can happen during charging, unlike with an ICE refuelling. However, if in a hurry, todays EVs can extend how long your road trip stops can take.
The Achilles Heel: Road Trip Recharge Ratio.
What Is Recharge Time Ratio?
For every one minute of rapid charging, an EV should provide a number of minutes of driving at highway speed. I call the number of minutes the ‘recharge ratio’.
So, with a recharge ratio of 6, 10 minutes charging should give one hour of driving, and 20 minutes recharging should give 2 hours of driving.
The Missing EV spec: Driving Time/Recharge Time Ratio.
The lack of a specification like this makes it hard to compare different EVs. Consider, specifications typically gives as “charges from 10% to 80% in XX minutes”.
Driving at any constant speed requires a number of kilowatts every hour, and recharging can replace a number of kilowatts ever hour. If the rations between these number is 4, then four hours driving would require 1 hour of charging. Double the battery size will double both numbers, but would not change the ratio of driving time to charging time.
What will change the ratio, is speed. The faster you drive, the lower the ratio, so you will gain less time from driving faster in an EV. Just as engine power can be a curved graph, so would the Driving Time/Recharge Time ratio. However, if the national speed limit is 110 km/h (68.35 mph) as in Norway, then the ration at this speed would be most important to you. In France or Germany, the ratio at 130 km/h (80.8 mph) might be more important, and what is most important will change will local conditions.
Real World Driving Time/Recharge Time Ratios at 110 km/h: from Bjørn Nyland.
EV vlogger Bjørn Nyland tests car using his 1,000 challenge in Norway. His reference time for the challenge ‘using a fossil refence car‘ is 9 hours 25 minutes (9:25) at an average of 106.2 km/h. While in theory if remaining exactly at the speed limit and without stopping at all, the journey could have been 9 hours and just over 5 minutes, this is not the real world, and 20 minutes lost between one refuelling stops and traffic delay when driving 1,000 km is very efficient.
Comparing a selection of cars from Bjørn’s data using their excess time over the reference and being recharge time to calculate the ratio at 100 km/h reveals:
- 18.8 – 2021 Telsla Model 3: 18.8
- 16.1 – Hyundai Ioniq 5
- 10.3 – Audi e-tron 55, Mercedes EQA, Tesla Model X
- 9.4 – Ford Mustang Mach-E LR RWD
- 8.7 – BMW iX3
- 8.1 – VW ID4 82 kWh
- 6.3 – Tesla Model S P85
- 5.9 – Mercedes EQC 400
- 4.5 – Ford Mustang Mach-E LR AWD
- 3.8 – Audi e-tron 50
As you can see, older cars perform much worse, and newer cars such as the Lucid Air, or XPeng models using 480 kw charging, should perform even better than any on this list so far.
Data For Driving Time/Recharge Time Ratios at 90 km/h and 130 km/h: Battery Life.
The you tube channel ‘battery life’ does full range tests in Germany at both 90 km/h and 130 km/h. These videos are interesting and and give insights into other factors affecting range, however tests focus on driving cars from full charge until range is fully used and then charging until the battery is completely charged. This is useful data, but differs a little from what you would get in the real world, as you will charge when convenient and you want to stop, and will get best results with most cars if you don’t wait for an absolutely full charge as opposed to 80% or 90%, unless want to be stopped for long enough for a full charge for other reasons.
People Need Recharging Too: Human Recharge Ratios.
When on a road trip, it is recommended, that the driver rests every 2 hours for around 15 minutes. Some people ignore these recommendations, and other instead use multiple drivers, but until there is genuine level 4 or level 5 self driving cars, it is recommended to take the breaks even if swapping drivers.
Fifteen minutes every hour would be a ration of 4 to 1, fifteen minutes every 2 hours is a ratio of 8 to 1. This means for any vehicle with a recharge ratio above 8 to 1, the car in theory requires less recharge time than the driver.
In practice, not every ideal stop for humans would have the ideal car charging equipment. There are road trips where the it is the journey and not the destination, and these trips normally have more generous windows for charging, but when it is all about the destination, the ideal EV would have a ratio of 16 or better, and currently there are only two entries on the list that comply. Fortunately, at least half of the mainstream EVs being released in the next year would be capable of 16, and things will only get better after that.
Meantime, look carefully at the recharge ratio when considering an EV that will do lots of road trips.
The Fine Print: Be Aware Factors Affecting Real World Recharge Ratios.
Its Cruising Speed, Not Average Speed, That Is Important For Efficiency.
There are many reports online of peoples real word experiences, but caution is needed when inferring what your experience will be. I have seen calculations where people make comments such as:
- ‘The average speed was only 90 km/h, not 110 km/h, so the real consumption would be higher’.
- or ‘we were delayed by road works, so it was necessary to drive faster to make up time’.
The logic here is a trap. Consider three trips:
- A person drives for 1 hour at 110 km/h.
- Average speed 110 km/h.
- A person drives for 30 minutes at 110 km/h, waits 15 minutes for roadworks, then resumes 110 km/h for 30 mins.
- Average speed 88 km/h.
- A person drives for 45 minutes at 130 km/h, then 15 minutes at 50 km/h.
- Average speed 110 km/h
Number 1 is obviously all travelling at 110 km/h. But number 2 is also all travelling at 110 km/h. The 15 minutes stopped lowered the average speed for the day, but had no impact more impact on the average speed the car travelled at when it was being driven, then if the person in number 1 was asked to wait at the finish for 15 minutes before calculating the average. For number 3, the car travelled 97.5 kilometres at 130 km/h, which is 90% of the distance. The 15 minutes of driving slower will not suddenly recover fuel used when driving faster.
Many Other Factors Effect Efficiency.
Internal combustion engines are less efficient at best, and are rarely at best, which results them being around 5x less energy efficient than electric vehicles in typical driving. This means everything else that effects efficiency becomes more noticeable in an EV. For this reason electric vehicles use the more efficient heat pumps in place of traditional air conditioners, as every thing that uses energy matters more.
The result is all of the following factors impact efficiency, and thus recharge ratio:
- Availability of Optimum Charging.
- Vehicles such as the Ioniq 5 could perform better in Bjørn’s test once faster chargers are available.
- Wheel size, with smaller wheels and taller tyres usually more efficient.
- 19″ wheels usually give longer range than 20″ or 21″
- Road conditions such are rain or snow.
- In heavy rain, consumption will increase.
- Temperature Extremes.
- Batteries operate best within a temperature range, and it can take energy to keep them within this range.
To Be Added:
- Portable or home charging by wind power is also possible.
- The Charging Network Trap.
- Safety: Recharging Vs Refuelling.
The Future: Wireless and Vehicle to Grid
Wireless Charging: The Next Step?
Wireless Charging At Home: Still rare, but becoming available now.
Having to plug in each night when you park may not take long, and if we can remember to charge our phones, it may not seem to much of a burden, but just imagine if as you a pulling up, the car automatically guides itself to the right position to recharge. This is new, but the it is already down as an option with Hyundai Genesis EV60 and the BMW530e. As the WiTricity wireless charging follows an open standard, and is said to be as efficient as a cable, wireless charging could take over. VW aims to wirelessly charge a Porsche Taycan to 80% in 10 minutes.
Wireless Charging On The Move: In Early Trials.
Like the technology used by our smart devices, the system needs vehicle-mounted receivers to work. According to the company, this is something that has not been implemented yet as a factory feature by any renowned carmaker but can be easy and cost-effective to add on existing and future EV models.
In terms of logistics, the only inconvenience is that a portion of the asphalt needs to be removed and replaced. Other than that, the system can connect to existing power grids without the need for additional infrastructure or transformation stations. It uses management units placed on the sides of the road to communicate with the receivers on the vehicles and transfer energy.
ElectReon is involved in multiple pilot programs to test the feasibility of this technology. Recently, the company has completed the deployment of its dynamic wireless charging system on a 1.65-km (1.02-mile) public road in Gotland, Sweden.Sweden Successfully Tests Wireless Charging Road Set to Revolutionize Mobility
Just as wireless charging is becoming the normal with mobiles, we could move to a world where ‘stopping to refuel’ just doesn’t happen. We recharge for the lowest cost at home overnight, particularly if we have solar power, and on the move on the highway on a road trip, all for lower cost than refuelling an ICE vehicle.
- Wireless Charging For EV Buses & Trucks — Interview With WAVE CEO, Part 1
- This Road Wirelessly Charges Electric Cars as They Drive
Vehicle to Grid.
Already, the Ford F150 lighting supports Vehicle to grid.
“The companies will test the ability of Ford’s new F-150 Lightning electric vehicle to send power flowing back to a house and connect with the grid, Ford Chief Executive Officer Jim Farley and PG&E Chief Executive Officer Patti Poppe said during an event Thursday night at the CERAWeek by S&P Global energy conference in Houston.
Ford’s battery-powered F-150 is the first of its kind that can be used as a backup power source. PG&E will test five trucks this year, Poppe said in an interview.”https://www.bloomberg.com/news/arti…test-electric-truck-as-power-source-for-homes
In the future, vehicle to grid could become an essential feature. In 2021, vehicle to grid is merely another future technology, that means any home charging infrastructure installed now may become obsolete.
How does recharging work?
All recharging requires providing a DC voltage across the terminals of the battery, with a potential difference greater than the internal voltage of the battery at that time. The greater the difference in these two voltages, the greater the current that will flow into the battery.
AC Recharging: The Onboard Charger (OBC).
Battery charging requires DC, so starting from AC power, requires the OBC circuitry in the car to do all the real work.
Typically the first step will be a Power Factor Correcting (PCF) circuit which converts the incoming AC power to DC power using a direct bridge and capacitor, resulting in AC converted to raw DC, while ensuring the load on the AC appears as close as possible to a pure resistive load.
The next stage, normally an LLC converter, where L=inductor, and C= capacitor, takes the raw incoming power, and converts this to either a desired voltage, or whatever voltage will ensure the desired current. Since the battery provides the resistance, and V=IR, the same result can be obtained either by tracking voltage, or current.
Overall, the efficiency of AC charging is all determined by the car.
For AC charging a “Wall box”, sometimes misleadingly called a wall charger, and correctly called EVSE or Electric Vehicle Supply Equipment, is used. Such equipment can be directly wired for higher current and/or three phase electrical power, contained a high voltage relay to ensure the connector and cable only have power when charging, and include a socket specifically designed for the high current AC power.
DC Recharging: The External Rapid Charger.
With DC charging, all the conversion to the DC with the desired voltage and/or current is provided by the “charging station”, leaving on the logic to continually determine either the required current, or voltage required to the car. Although all DC charging points have power specified as kW, in reality they have limits to both voltage and current, and the specified power is only delivered to a car requesting maximum voltage and current. For example a 50kW CCS charger can deliver 100Amps at 500Volts. Since cars usually want less than 500 volts, they will not get the full 50kW.
USA Specific Data: Voltage, Plugs and Batteries.
A large percentage of information on EVs originates from the USA, which had 3 differences to the rest of the world:
- 100v-120v electrical supply, North America, Japan and US territories.
- Tesla vehicles use proprietary plugs, as opposed to standard plugs used in Europe, Asia, Oceania.
- All vehicles, including Tesla, so far use ternary batteries with more limited charging curves, whist outside of the USA, Teslas can already be using LFP batteries.
Batteries Charing Profiles: LFP vs Ternary.
Batteries In Use.
As of early 2022, all EVs by traditional car brands use ternary batteries, as do all Teslas in the USA, and longer range Teslas elsewhere. Within China, LFP batteries are around 50% of all batteries as of early 2022, but outside China, LFP is only in some Tesla models and all exported BYD vehicles.
Characteristics: Ternary Batteries Vs LFP.
These NCA and NMC batteries have so far given a higher capacity for the same weigh and volume, but come with a number of drawbacks, and in comparison to LFP batteries ternary batteries:
- Present a far greater fire risk.
- Have a shorter lifespan, around 1/2 of LFP batteries.
- Require more careful charging, with charge above around 80% being undertaken at much slower charging rates, and above 90% to be used only one road trips on occasions wher maximum range is required.
Caring For Ternary Batteries.
Advice on battery care varies from car to car, as difference cars implement different strategies to help manage ternary batteries. Some report a battery capacity, and a separate, lower, “usable capacity” that prevents using all or some of the battery capacity that would require cautious slower charging and less frequent use.
Generally if the manufacturer provides as time for charging from, say 10% to 80%, then that is the range where the battery can if conditions are correct accept full fast charging, and outside this range, charing should be slower.
CCS Charging: What charging speed can I really get?
There are Tesla superchargers which follow their own standard, although outside North America and China they also use the CCS system, but for most of the world charging is all about CCS.
The original CCS standard provided for 500 volts and 100 amps. Power = volts x amps, so this provided for a maximum of 50,000 Watts, or 50kW. However, if your car runs on a lower voltage, and most are around 400 volts, there is still only 100 amps available. On a 400v car, this will mean 40kW maximum. So do not assume the rating of the charge station is what you will get, and there are many 50 kW charge stations in the field.
The next standard, CCS 2.0, not to be confused with CCS type 2 plugs, increased the maximum charge to 150 kW (I think but need to confirm as 500v 300a), and
The latest to 350 kW standard provides for 350 amps at up to 1,000 volts. So on an 350kW charge station, an 800v vehicle could charge at 280 kW and and a 400v vehicles at 140 kW.
Recharging Summary and Conclusion.
There are a few key takeaways on the situation right now, in late 2021, for people moving from ICE vehicles:
- Recharging on road trips is a step backwards from with ICE Vehicles, although in most cases, in practice, it can depend of if you also recharge the humans when you stop.
- When not on a road trip, for those with access to home charging, recharging is a significant step forward from the refuelling experience with ICE vehicles.
- Without home or office recharging, EV recharging is problematic and a step backward from the experience refuelling ICE vehicles.
The biggest problem is charging speeds, but that of finding solutions for those who cannot charge at home.