One Finite Planet

EV Battery swapping: Recharge or Refuel?

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My keyboard is powered by batteries which convert stored chemical energy to electricity. For more energy, I can either 'refuel' by swapping batteries for instant new energy, or 'recharge' the batteries which takes longer but is more efficient.

Every car ever produced is also powered by chemical energy, and either combusts the chemicals to release heat, or converts the energy to electricity to power the car.

Why is it that, we rarely get to choose between refuel or recharge?

Recharge Vs Refuel.

There is a full exploration of recharging electric vehicles here, but there is an alternative offered in some areas already and becoming more available alternative, and it feels much more like refuelling a fossil fuel vehicle, because it is more like refuelling a fossil fuel vehicle: Battery swapping.

  • Recharge: Return fuel ingredients to their original state.
  • Refuel: Replace the old fuel with new fuel.

Battery swapping, or refuelling rather than recharging, takes around 5minutes for a full charge.

Refuel vs Recharge: Technical details.

It may be useful to consider why have the choice of refuel or recharge with EVs, but only ever bothered to refuel internal combustion engine vehicles.

Technically, if the used ingredients are not lost as exhaust but captured, you could recharge the fuel source for any engine. This is explained in detail in “Battery Reference: Recharging vs Refuelling“, but here is a bullet point summary.

Every car is powered by a chemical reaction. Examples of reactions to power cars are:

  • Internal combustion
    • Gasoline + oxygen → CO2 + Water + energy(heat)
      • 2 C8H18 + 25 O2 → 16 CO2 + 18 H2O ( simplified as per Wikipedia)
    • Natural gas + oxygen → CO2 + Water + energy(heat)
      • CH4 + 2 O2 → CO2 + 2 H2O
  • Steam engine car.
    • Coal + oxygen → CO2 + energy(heat)
      • C + O2 → CO2
  • Hydrogen Fuel Cell Car
    • Hydrogen + oxygen → CO2 + Water + energy(electrical)
    • 2 H2 + O2 → 2 H2O
  • Battery Electric Car (Cobalt Lithium Ion Battery)
    • To reactions, one each side of the battery
      1. LiCoO2 -> CoO2 + Li+ + e(electrical energy)
      2. Li+ + 6C + e -> LiC6

Each of those reactions requires chemical ingredients that are in their “charged up” state. Simplistic examples of the charging up processes are(see here for more details):

  • Biofuels
  • Gasoline
    • Photosynthesis + intense underground pressure over a very long time
  • Hydrogen
    • Electrolysis + intense pressure (so the hydrogen fits in reasonable size tanks) .
  • Battery
    • Apply electrical charge.
  • Refuelling:
    • Add the chemicals that have been previously charged up.
    • Plus:
      • As fast as refilling the chemicals
    • Minus:
      • More expensive, as more resources are uses, and fuel must be transported and prepared.
  • Recharging:
    • Take the chemical from the right side of the equation, and add energy to convert them back to those on the left side of the equation.
    • Plus:
      • No waste, no transport, just supply the energy to reverse the reaction
    • Minus:
      • All reactions take time, so you have to wait, but this is the most cost effective and sustainable.

If Recharging Is Best, Wouldn’t We Recharge Everything?

With Fossil Fuels and Other Hydrocarbons: Because Recharging is too slow.

Basically, they are called “fossil fuels” because they were ‘charged up’ by photosynthesis millions, if not billions of years ago.

It is easy to forget that with chemical stored energy, there is always a charging cycle that “stores” or adds the energy to the chemicals, preparing them as “fuel” with stored energy ready for use. Using the fuel in an engine, we get that energy back on demand, plus ‘spent’ fuel.

With all hydrocarbons, the “charging” formulae is:

CO2 + Water + energy -> fuel + oxygen

All hydrocarbon or alcohol fuels are “charged” well in advance of use, because ‘charging’, usually by photosynthesis, takes a long time, and a lot of space. Usually it is done by plants and photosynthesis, because the “charging” process takes as long as it takes plant to grow. While something huge on a long journey like a space ship travelling between stars would have no choice to but to “recharge” on board, cars using these all rely on fuel prepared elsewhere and in advance, rather than wait for the plants to grow.

With fossil fuels, the charging up happened millions of years ago, and do not worry about recharging, while with biofuels we “charge, or prepare fuel, at the same rate we consume it.

“Recharging” in car is just not practical.

Hydrogen Cars: Because The Problem isn’t just recharging, but Also Storage.

It would be easy for a car to simply condense the water from the hydrogen fuel cell. Then connect to an electricity supply and run electrolysis. Except…. hydrogen is a gas that takes up too much room so you need a very powerful compressor, and the vehicle would have a range measured in metres (or yards), rather than kilometres (or miles).

Battery Powered Products: Because It Can Just Be Simpler To Refuel.

So with other types of cars, we generally refuel rather than recharge because in practice, recharging is impractical.

But what about with other battery electrical products, where recharging should always be an option?

The supermarkets normally have a huge supply of single use batteries, because people very often choose “refuel” rather than “recharge”. We could all buy rechargeable batteries, and recharge rather discard batteries once their fuel is exhausted, but clearly, a lot of people choose to just “refuel”. To be clear, I am not a fan of singly use batteries over rechargeable batteries, but their popularity vouches for their appeal.

So Why Recharge Electric Vehicles At All?

Recycling/Sustainability: It Is Essential To Recharge At Some Point.

The very problem with fossil fuels is that that “recharge” is not practical, which makes their use unsustainable. Simply switch to biofuels, and that problem is solved as the recharge is taking the water and CO2 equivalent to the emissions, and using energy from the sun to produce new fuel. There are questions about whether we have the land and resources to allocate to biofuels as opposed to food, but these questions arise due to population, rather than whether the process acceptable.

Hydrogen cars, as long as powered by green and not “blue” hydrogen, have a sustainable recharing process.

The single use batteries at the supermarket are more questionable, as while all the ingredients to in theory at least allow a combination of recycling and recharging, there is a question about them to recycling and sorted by specific ingredients, and there is the question of casing.

However, all vehicle battery swap schemes do tick the “recharge” box as the batteries are directly recharged to be ready used as the charged battery in a future swap.

There may be questions as to whether people who swap batteries all the time will neglect to care for batteries, thus reducing their “life” and time before a full recycle and not just a recharge is required, but otherwise, the impact on sustainability is small.

Cost.

It is not necessary to swap batteries every time at a battery swap station, but doing so is logically the most expensive way to charge a vehicle, although costs may be masked by sometimes being bundled with some vehicle purchases.

The swapped batteries still have to be recharged before they can be used again, which means battery swapping stations require the battery charging equipment, even beyond what rapid charge points do, because during a rapid charge, much of the charging circuitry is in the car. Then battery swap points require the physical swap machinery, and the swap station becomes responsible for the battery care.

Overall:

  • Battery swap stations need to be more expensive than rapid charging stations to be profitable.
  • Rapid charge stations need to be more expensive than home charging to be profitable.

If people who use battery swapping only on road trips when they would otherwise use rapid charge stations, the cost difference would be small, particularly if the number of road trips per year is small, but it is the most expensive way to charge.

Vehicle Batteries Are Not Easy To Swap.

With most electric vehicles, such as electric bikes, scooters or electric motor scooters, battery modules are small enough an light enough for people to swap themselves. Far from AA batteries and weighting just under 10kg (22lbs), modules are manageable.

However, modules that can be swapped by the consumer are only part of a dream future for Electric Car, Battery swapping of current car batteries, is unlike, electric scooters and other battery vehicles, not something that can be done at home, or by the private vehicle owner themselves.

Swapping Isn’t As Convenient As Charing At Home, So When Is it Worth The Cost?

The answer for most people is: rarely.

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

It should be noted that given most people charge at home almost all the time, and battery swapping cannot compete for either convenience, or price, with charging at home, for those who can charge at home battery swapping is only for road trips, which most people don’t do that often. Many brands, including Tesla and While VW have rejected the idea of battery swapping on the basis of market research, Tesla designed the system into the Model S and introduced in in California.

EV Refuel (Battery Swap) Advantages.

It’s faster.

In theory, fast charge times for EVs can be as low as 15 minutes and may get even faster, but in 2022 in in practice, even fast charging can take as long as an hour. Putting in new fuel in the form of a new fully charged battery pack(s) should never exceed 5 minutes. Sure, recharging the existing battery pack is the best way when you have the time, but you do not always have that time?

No More Needing A Driveway: A Future Possibility?

In future, it may become possible to have even cars with modules that consumers can change themselves, but this benefit applies only to those able to swap their own batteries, but such people, it is a significant benefit.

The low cost and convenience of recharging in the driveway or garage overnight for most owners becomes one of the best features of an EV, but what about all those owners who need to park on the street? Or those who park in apartment spaces without power for recharging?

When a vehicle owner can simply bring their battery module(s) to their own charging point, then even those previously unable to charge at home get all those same benefits.

The Principle Of Battery Swap: Best Of Both Worlds.

With electric vehicles, there are two types of recharging: at-home and road-trip. Most EV owners almost always charge overnight when at home, as it is very rare normal people drive more than the range of an EV during a day, as this generally only happens on a road trip. On a road trip, that second type of charging, road-trip rapid charging is needed, because unlike when home at night, the charge needs to be done as fast as possible. Another difference is, unlike when charging at home, you can’t just add the electricity to your power bill, so the electricity needs to be purchase from the reseller who runs the charging station.

The two main charging types:

  • Overnight at home.
    • Lowest cost electricity, but very slow charging.
    • EV owners often can go months needing no other charging.
    • A totally satisfactory experience.
  • Road trip rapid charging.
    • Higher cost electricity, but still far lower running costs than gasoline or hydrogen or other alternatives.
    • Rapid charging times can take an hour, and although many newer vehicles are faster (as low as 18 minutes), even the fastest recharge is still slower than refuelling an internal combustion car.
    • An experience than could do with improving.

The perfect battery swapping system allows charging the battery module(s) you have at night each night at the lowest rate as available at home, or when desired, going to a station and swapping. This can even allow swapping battery modules for a longer range battery module when on a trip.

Battery Swapping EVs vs Hydrogen Cars.

On the other hand, given battery swapping is at least as fast, and more economical, than hydrogen refuelling. Also, as there are now EVs with longer range than that of any hydrogen vehicle, battery swapping makes the case for hydrogen gets even weaker.

There are plans for 540 hydrogen refuelling stations worldwide by 2027, compared to the 24,000 battery swapping stations already planned by 2025. Note that while battery swapping logically always cost more than recharging as the swapped batteries still need to be recharged, battery swapping is cost competitive with not just the expensive hydrogen refuelling, but also gasoline refuelling, and people can opt to recharge when at home, and only pay the extra for battery swap (refuel) when on trips.

Battery Swap In Practice: Enabling The Refuel Option For EVs.

Example 1: Interchangeable Lens Cameras.

Sony Camera and 2 batteries.

Camera made mostly by Sony, Canon, Nikon, and Panasonic all use batteries which can be either ‘refuelled’ (swapped) or recharged.

Wen a photographer may need more charge than possible from one battery during a day shooting photos, they can simply carry a spare fully charged battery. Then rather than connecting the camera to a USB charger when the battery is low and wait while ti recharges, the battery can be swapped for almost instant return to the camera being fully charged.

A new camera will normally only include a single battery, and many people will never need a spare, so they can simply recharge the camera after a day taking photos. Each brand of camera has its own battery types, and these even change from model to model. However standardisation of batteries is not needed as photographers bring their own batteries with them.

Example 2: Gogoro Electric Scooters.

Gogoro, the company behind what has become the de facto standard for swappable batteries in light electric vehicles, has just unveiled the world’s first swappable solid state EV battery prototype.

Gogoro unveils the world’s first-ever solid state swappable electric vehicle battery

Gogoro Inc., a Taiwan-based electric scooter maker and battery-swapping platform, announced Tuesday the two new strategic initiatives that drive momentum in Indonesia, the world’s third largest two-wheel vehicle market.

The firm said in a statement that it has partnered Hon Hai (Foxconn), Indonesia Battery Corporation (IBC) and Indika Energy to jointly develop a sustainable electric vehicle ecosystem in Indonesia that establishes the foundation for an open industry.

The partnership initially includes the four founding members but is expected to include additional mobility companies in the future.

Taiwan’s Gogoro inks two partnerships to establish an open electric mobility and battery swapping ecosystem in Indonesia

Note that other brands, such as Yamaha, also use the Gogoro module specification for their scooter. The Gogoro battery case has become a de facto standard, but this is possible because the company has been open with the specification and allows competitors. The result is that electric scooters in several counties can all ‘refuel’ at charging stations just like gasoline/petrol scooters can refuel at conventional fuel stations. In Taiwan, there are already more Gogoro swap stations than conventional fuel stations.

However there is also a Japanese consortium on battery swapping: Gachaco, and I have yet to see how these standards align or compete.

Swap or Charge – Total Flexibility

Swap batteries in 6 seconds4 at any one of GoStation® around Taiwan, or charge through any standard wall outlet using the GoCharger® Mobile. The perfect dual combination of swap and charge solution – only experienced and enabled by the Gogoro Energy Network.

Gogoro Website.

This means not only does battery swapping become an option, but also charging at home becomes possible for those while no power where they park. Remove the battery and bring it inside your home to charge.

A National Swapping Scheme: India.

India is introducing an official rather than de facto standard for battery swapping. Whether this scheme will goes beyond the battery size of Gogoro, I do not know.

Tesla: Early Battery Swapping.

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.

We built the pack swap into the car because we weren’t sure if people would want to choose the pack swap or not. We thought people would prefer Supercharging, but we weren’t sure, so that’s why we built the pack swap capability in. And based on what we’re seeing here, it’s unlikely to be something that’s worth expanding in the future, unless something changes.

The Verge, 2015: Tesla sounds ready to pull the plug on promised battery-swap technology

Despite Elon Musk demonstrating a battery swap live in 2013, he never seemed to cool on the technology over time and while the Model S was designed for battery swapping, the swap stations were never widespread.

NIO (et al) Battery Swapping.

Four companies – automakers Nio and Geely, battery swap developer Aulton and state-owned oil producer Sinopec (600028.SS) – say they plan to establish a total of 24,000 swap stations across the country by 2025, up from about 1,400 today.

Inside China’s electric drive for swappable car batteries

Currently only NIO, implements a battery swapping scheme at scale for cars. It is not battery modules, but the entire battery of the electric car that is swapped, but as above, other brands do plan to join.

It is currently only widely available in China, as are NIO cars, but NIO started going global in 2021 and will accelerate global expansion in 2022, and opened the first battery swap station in Europe in Sept 2021.

Over the past year, NIO has dramatically accelerated its innovative battery-swapping technology for electric vehicles by introducing a new Battery-as-a-Service (BaaS) subscription model and its NIO Power Swap Station 2.0. Users can now drive into any one of NIO’s 517 Power Swap Stations around China to get a fresh battery pack installed in about five minutes. That’s roughly the same time it takes to fill up a tank of gas.

NIO Web site: October 2021.

The limitations of the NIO systems are:

  • As opposed to modules, large, expensive specialised equipment is required to swap batteries.
    • This makes stations expensive, and rules out consumers being able to swap batteries.
  • With a standard of battery sizes and mounting schemes agreed between manufacturers, each brand would need it’s own chain of battery swap stations.
  • Even within each brand, over time the number of battery sizes and shapes to manage could easily become unwieldly.

The NIO scheme ticks many boxes, but it is expensive to operate. Nor does it provide access to charging at home for people who park on the street, as current car batteries are just too heavy for consumers to be able to remove batteries themselves and carry them into the house when at home.

CATL Battery Swapping.

CATL is the worlds largest battery maker, with over 1/4 of the world market in EV batteries, supplying amongst others, GM, Tesla, VW and BMW.

CATL is effectively betting that the speed of recharging EVs will continue to be an issue for years and that EV owners, at least in some regions, will pay for battery swaps that will take just a couple of minutes—and the ample infrastructure needed to do so. 

Autoweek, Jan 2022: CATL Is Getting into EV Battery Swap Stations

Portable battery units: ZipCharge Go et al.

Other units may enter the market, but the ones I know of so far are the roadie and the ZipCharge, with the Zipcharge being the most promising at this point, although the specifications and price are clearly still being finalised with production planned for Q4 2022. So far, a range ‘boost’ of around 64.4km(40 miles) is promoted, and currently 4kWh and 8kWh units are being considered. A unit like this would allow getting a small and slow boost of charge even in locations where recharging is not otherwise feasible.

What Does the Future Bring?

Limitations Of Current Technology

Electrek has already discussed the possibilities and limitations of Gogoro’s upcoming solid state battery with 2.5 kwh per brick at a weight of 9.5kg. This is an energy density of 263 kwh/kg, and although this incudes the case, there are suggesting much higher energy densities suggested from future solid state batteries.

The famous “$5,000 Wuling Mini” electric car (don’t get me started on how it’s not really a “$5,000” car) has battery options of 9, 13, and 26 kWh. The first two would require between three to five Gogoro batteries. Pulling out 10 batteries for the highest-range version might be a bit much. At a certain point, it would be ridiculous to have a dozen removable batteries, but a handful could mean the difference between EV ownership or not for those that simply don’t have a good place to plug in.

From “Electrek’s Take“.

The only thing this analysis misses, due in part to space constraints, is that there are compelling use cases where not all modules need be swapped. But yes, even with the upcoming solid state units, a 50kwh electric car would require 20 of these modules. For more typical full range 75kwh. or large long range 100kwh battery vehicles, 30 or 40 modules would be required. But batteries have improved in density significantly over the past decade, and are projected to keep improving, so it becomes a matter of determining what is needed now, and then calculating how much improvement is required before each compelling use of modules become feasible.

The goals of a battery swap module system would be:

  • Owners can change battery configuration according to their needs, and as technology improves.
  • Fast refuelling is enabled for road trips, largely eliminating recharge time concerns.
  • Owners could rechange battery modules outside of the car, allowing charging batteries even when cars cannot be parked where they can be recharged.

To achieve all of these, you need battery modules practical for a consumer to manage, with sufficient total capacity.

The big question is, can either:

  1. Any foreseeable battery technology bring a 4x or 5x energy density improvement?
    • or
  2. Can any practical design be workable for larger modules, as might be required in cars?

At 9.5kg, one brick is about as much as could be assumed to be carried without wheels. Two, at 19kg is possible, but many people would find this too heavy.

It should also be noted that charging a battery pack outside the car need not be a solution for fully charging battery capacity of the entire car, and as 20kwh of capacity is enough 100km of driving which covers the normal commute. The goal is not replace all charging needs by charging modules at home, just to enable lost cost charging to be providing a significant amount of regular charging.

Overcoming the Limitations.

Aviation has the same weight problem with batteries. They are too heavy. Aviation needs batteries with at least double the power to weight of Gogoro batteries to be viable, and in fact cars are still significantly impacted by the weight problem, with gasoline having around 50 time the energy per unit weight of current batteries. For these reasons, there is a lot of work focus at batteries with a an increased energy per unit weight. Batteries have already improved over 5x from the lead acid battery to the the energy to weight of the batteries lead acid batteries from the new Gogoro battery, and it is feasible they will improve in the next few years by another 4x, reaching around 1kWh/kg.

Promises and even production runs of batteries with around 500Wh/kg, or close to double that the new Gogoro modules new battery seem to be almost ready for production, and 1kWh/kg batteries, are clearly technically possible.

At that 1kWh/kg, a battery the weight of the Gogoro would provide 10kW/hrs. This would completely transform electric vehicles. A car with up to 10 battery slots could normally drive around with only 3 or 4 modules as that is plenty of range for every day use. On road trips, it could mean swapping 8 modules if 80% of charge has been used, but that should still only take a few minutes, and only be needed after around 650 km or 400 miles of driving. Not only would the car be carrying less weight because these batteries are lighter, but some could be left at home charging during the day, and also providing backup power at home.

Not only could those needing to park on street, or in another location not connected to home power, charge their battery modules at home by bringing them inside, when not on road trips and therefore needing far less range, they could leave most modules at home. The modules could at these times function as home batteries, charging from solar and providing battery backup to the grid.

Quite possibly the Gogoro modules are not the ideal shape for a car, and something more like the BYD blade possibly being a more appropriate shape, but we are also talking of future when batteries are 1/4 of current weight and volume.

The Potential.

The Future: 10kWh Modules.

The So now picture a future where battery modules similar to the size and weight of a Gogoro batteries, have reached that 10kWh capacity through the introduction of new battery chemistry.

“Normal Days”: 4 Modules Required.

City driving should only require 4 of these modules. The Mazda MX-30 is positioned as the perfect “city car”: a car that is exactly all that is needed when not on a road trip. The MX-30 has a 35kWh battery, just 3½ modules. Why carry more than 4, unless going a road trip?

Cars Could Be Far Less Expensive: Just Buy, Or Lease Batteries Separately.

Buying your first electric car? Why buy battery modules at the same time? The lower running costs of an EV will allow you use the savings to rent some modules for a while, and even have enough savings to save up to buy some.

Buying your second or third electric car? Keep your batteries from the previous electric car. Already most batteries are expected to outlast the rest of the vehicle.

Renault with the Zoe, and NIO with several models, already offer the choice of buy or lease batteries, and NIO combines this with battery swap, but none yet leverage the power of modules, largely because todays battery modules would be too bulky. To leverage the real power, you need tomorrow’s battery technology, but it will come.

Home Charging For All.

This is the a clear obvious advantage, already realised for motor scooters as show in the promotion by Gogoro referenced above. With increased battery density , this same advantage will be avoiable to to car owners as well.

Increase Range On Demand.

Once battery densities increase, and thus batteries of the same range require less space, finding enough space to fit modules for a much longer range than that provided by todays cars is simple, but does everyone need that longer range? Most of the time, the answer is “no”. Most people would almost never need a car with, for example, 12 slots allowing 120 kWh. Almost never. But making a car with 12 slots would no overly tax the space for batteries, and if the car is sold without all slots filled, would do little to increase price. So everyone could have 120 kWh battery for a rare occasion just by renting a few extra batteries for those normally “spare” slots. But if you need to travel some huge distance between battery swap points for some special reason, just pack a few extra modules. Yes, if you have more modules than slots, you would have to stop to swap modules, but not for very long, and a brief stop every two hours is recommended anyway, even if only to change drivers. Physically swapping some batteries would add very little time if this was ever needed.

End Range Anxiety.

Whatever range needed, just carry the required number of modules. No one need ever start any journey with enough range, or fear the vehicle they are buying will not have the range for their needs ever again.

Conclusion.

The practicality of battery swapping, is hugely dependant on the size of the batteries. Electric scooter riders can physically carry their battery modules, which opens up a new world of flexibility for motor scooters, but for cars, the batteries are just too big, even when split into modules, for anything like that world of flexibility.

However, just as before the increased energy density of lithium ion batteries, EVs were not really a practical cars, emerging battery technologies with improved energy densities will completely transform what is possible with battery swapping for EVs.

Providing battery technology can reach that 1kW/kg level, swappable battery modules could revolutionise electric vehicles once again.

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