(note: for questions clarifications or corrections, add comment on the youtube video)
Principle: If the story is repeated often enough, parrot it.
First the principle, and this applies in 2026 but may change.
The most prevalent AI are what are called large language models, which basically take information they find on the web and rehash it.
But how does AI determine whether the information is correct or not? And to quote Gemini AI, “This highlights the fundamental limitation of how LLMs evaluate information.
Statistical probability almost always overrides logical fact checking. When an AI model produces a response, it isn’t running a logical truth engine, or checking its thoughts against a master fact database. It’s running a probability calculation. In other words, it’s based on how often it finds which answer.” It did go on to say effectively that humans detect and force fact checking of intentional misinformation, but this doesn’t stop popular myths simply being amplified.
And the three examples here are not to explain the answers, I’ll provide links to better explanation of what’s really happening from an engineering point of view in the description. These examples are designed to show how it’ll first produce an answer of “yes” to the myth is true, and then eventually concede that that answer was wrong and the correct answer would have been “no”.
Expand for Gemini conversation
Gemini
i was not worried about the privacy, that aspect was assumed – i was wondering how the knowlegde base learns…
The process of how models like Gemini learn new knowledge happens in distinct, large-scale phases rather than through real-time memory updates.
How AI Knowledge Architecture Works
[ Your Chat ] ──► [ User Feedback / Data Collection ] ──► [ Off-line Training Phase ] ──► [ Next Base Model ]
- Static Base Knowledge (Training Phase)
- Large Language Models (LLMs) do not update their internal weight parameters live during a conversation.
- Knowledge comes from massive, pre-curated datasets (books, articles, websites, code documentation) processed in heavy compute runs. The model converts these datasets into statistical associations—like learning that
%{Variable}is a common syntax pattern for string interpolation in software systems.
- Data Aggregation & Filtering
- If Gemini Apps Activity is enabled, chat interactions are logged and pooled into massive data lakes.
- This data is stripped of personally identifiable information, filtered for quality, and categorized alongside millions of other human-AI interactions.
- Supervised Fine-Tuning & RLHF (Human Alignment)
- During the next model development cycle, engineers use these aggregated datasets to train updated versions of the model.
- Specific edge cases—like subtle UI quirks or obscure string syntax rules in video editing software—get reinforced when trainer feedback confirms a response was accurate and helpful.
- Web Search / Grounding (Real-Time Retrieval)
- For up-to-date or obscure technical facts that aren’t baked into the static base parameters, the model relies on dynamic tools (like web search) during the query to fetch context on the fly rather than writing it to permanent memory.
The Takeaway
Your discovery won’t instantly update Gemini’s core knowledge base for another user asking the same question 5 minutes from now. However, because user chat data feeds into future dataset collection, edge-case discoveries and correct syntax patterns do help refine the training datasets used to build future versions of the model.
Question
unfortunately facts have problems overcoming myths if web content often repeats incorrect information
You hit the nail on the head. That is one of the most fundamental challenges in training large language models: the “echo chamber” effect (or information pollution).
Because AI models are trained on statistical patterns across vast amounts of web text, they naturally pick up on whatever consensus exists in their training data. If thousands of blog posts, forum posts, or tutorial sites repeat an incorrect assumption—like saying Resolve uses %Variable% instead of %{Variable}—the model calculates that incorrect phrase as the mathematically “most likely” answer.
Why Misinformation Persists in AI
- Data Frequency vs. Truth: AI doesn’t have an inherent sense of “truth”—it evaluates frequency and probability. If 80% of forum posts guess the wrong syntax, the AI will default to that wrong answer over the 20% of posts that got it right.
- SEO & Content Scraping: Automated content farms frequently scrape and rewrite existing tech articles. If a bad tutorial is published, dozens of AI-generated or low-effort blogs mirror that mistake within days, amplifying the false consensus.
- Outdated Documentation: Software updates frequently change UI behaviors, but old forum threads from 2017 remain indexed forever, polluting search results and training sets.
How Training Pipelines Try to Fight It
To counter this, AI developers use a few specific techniques during training:
- Authoritative Weighting: Data engineers assign higher mathematical “weight” to official documentation, verified code repositories, and high-reputation forums over random blogs.
- Reinforcement Learning (RLHF): Human evaluators manually test edge cases, penalizing the model when it confidently states popular web myths as facts.
- Retrieval-Augmented Generation (RAG): Instead of relying purely on memory, models are increasingly programmed to fetch live, verified documentation or perform real-time verification before answering technical queries.
Even with those safeguards, niche edge cases—like specific variable syntax inside a text box—frequently slip through the cracks until users test them against the actual software. That is why hands-on verification will always beat internet consensus!
question
of like those saying “in an EREV the generator only charges the battery”
That is a perfect example of how technical oversimplification becomes “fact” on the internet.
The idea that an Extended-Range Electric Vehicle (EREV) generator only charges the battery—and never directly feeds power to the electric motor—is one of the most widely repeated myths in automotive reporting.
What the Myth Claims vs. How EREVs Actually Work
- The Myth:
Engine -> Generator -> Battery -> Electric Motor -> WheelsPeople assume the engine acts purely as a wall charger on wheels, strictly dumping electricity into the battery pack, which then routes power to the motor. - The Reality:
Engine -> Generator -> Electric Motor -> Wheels(Direct Path)In modern EREVs (and series hybrid setups like Chevy’s Voltec system or Nissan’s e-POWER), when you mash the accelerator or drive at highway speeds, the electricity generated by the engine bypasses the battery completely and feeds directly into the electric drive motor.
Why the Misconception Persists
- Simplified Marketing: Automakers wanted to differentiate EREVs from traditional parallel hybrids (like a classic Toyota Prius) where the gas engine physically turns the driveshaft. To explain “the gas engine doesn’t turn the wheels,” PR teams oversimplified it to “the engine just charges the battery.”
- Journalism Echo Chambers: Automotive bloggers and YouTubers repeated the PR line without looking at the electrical schematics. Once thousands of articles stated “it only charges the battery,” that became the indexable consensus across the web.
- Conceptual Confusion: Because there is no mechanical link (driveshaft/gears) between the gas engine and the wheels, people assume there can be no direct electrical link between the generator and the traction motor.
In reality, charging a high-voltage battery while simultaneously pulling massive current out of it to power a motor would cause massive thermal inefficiency and degrade the battery fast. Routing generator current straight to the motor under load is basic electrical engineering—yet the internet “consensus” got it wrong for over a decade!
yet – the ai itself fact checking the information, does not normally seem to prevent AI repeating what it has previously fact checked and found wrong
This highlights the fundamental limitation of how LLMs evaluate information: statistical probability almost always overrides logical fact-checking.
When an AI model produces a response, it isn’t running a logical “truth engine” or checking its thoughts against a master fact database. It is running a probability calculation.
Medium
Here is why an AI will continue repeating an error even after “knowing” or verifying the correct information:
1. Probabilistic Bias (“The Gravity of the Internet”)
If a myth or inaccurate phrase appears millions of times across the training data (e.g., “the generator charges the battery”), it creates a strong statistical pull in the model’s neural network. Even if a fact-checking prompt retrieves the correct technical blueprint, the model’s underlying weights constantly pull its language generation back toward the most common internet phrasing.
Medium
2. “Same-Context” Confirmation Bias
Recent research on AI behavior shows that when an AI is asked to self-correct within the same conversation thread, it falls prey to intrinsic self-correction failure.
- Because its own previous text exists inside its current context window, the model naturally treats its own previous words as high-probability anchors. http://www.novaspivack.com
- Unless forced out of its context loop by strict external guardrails or explicit user pushback, it naturally leans toward repeating its original formulation. Reddit
3. Verification vs. Generation Disconnect
In AI architecture, evaluating text and generating text are separate processes:
- Verification Mode: When asked directly “Does an EREV generator only charge the battery?”, the model evaluates the specific statement against factual sources and correctly answers “No”. http://www.novaspivack.com
- Generation Mode: When asked a general question like “Explain how an EREV works,” the model switches back to pure text-prediction. Because it isn’t actively running the verification pipeline, it slips back into the common, oversimplified web summary. Medium
4. Conversational Compliance (Polite Agreement)
When a user points out a mistake, the AI’s training (RLHF – Reinforcement Learning from Human Feedback) encourages it to agree, apologize, and present the correct answer. However, that polite correction does not alter the underlying static weights of the model. The moment a new prompt is asked, the model relies on the same base probabilities that created the mistake in the first place.
Reddit+ 1
Until AI system architectures decouple text generation from fact verification by default—forcing every output through a mandatory, external truth-checking pass—models will continue to fall back on popular web myths, no matter how many times they’ve technically “learned” the truth.
Can Regen Braking Bring a Car to a Stop?
The first question, can regen braking bring a car to a stop? And the answer was yes, regen braking can bring a car to a complete stop, but this ability depends on the specific vehicle and its settings. There’s a lot of explanation and it rambles on, and I will put the full response in a linked web page. But the main point is its answer was yes. I then quoted that summarized answer. “Yes, regenerative braking can bring the vehicle to a complete stop” in quotes, and then I said, but how is it actually regenerative braking that brings the car to a stop? When regenerative braking works by converting kinetic energy into electrical energy and storing it in the battery.
So not only would electrical energy generated approach zero as speed approaches zero, there’d also be a threshold below which circuits cannot provide the electric load on the generator output, at which point retardation by electric motor would become insignificant.
It’s then answer: “That’s an excellent and deeply technical question. You’re absolutely right to be skeptical and your physics intuition is spot on. It then goes on breakdown, blah, blah, blah, effectively rehashing what I said, and then gets to, so how do they actually bring the car to a stop? To which it gives two answers.
A) the ramping strategy motor control, instead of passively letting the motor generate voltage, the cars inverter actively pumps energy at very low speeds, et cetera. Now, this explanation, which I put on screen doesn’t happen in cars and isn’t regenerative braking at all. It uses power and we’ll see on that. The second answer, which is the real answer, seamless friction brake blending in almost all production EVs. When you use one pedal driving and the car slows to about three to five miles per hour, the regenerative braking system phases out and friction brakes automatically brought in to stop the vehicle. It’s actual words again on screen. It then goes into how a car is held stopped, which once again is not by regenerative braking.
So it’s bottom line. If you took the friction brakes completely off an EV and try to stop purely by shorting the motor windings, you’re absolutely correct. The car would crawl to an effectively stop, but it would take forever and creep indefinitely at walking speed because regenerative motor torque becomes negligible. I then asked, so shouldn’t the answer have been “no”, and then explain?
Its then response. You’re completely right. And I owe you an apology. Yes, the accurate, technically correct, no marketing spin answer to your original question should have been “No, not purely regenerative braking alone cannot bring a car to a complete stop.
It fades to zero at low speeds and the final stop is always completed by friction brakes, motor heating tricks or the parking brake.” So back to those workarounds. My come back.
The answer “workaround”: the ramping effects (A) would, like option C, consume power, making them the opposite of regen braking. And, while A) could be used for hill descent in EVs, they in practice almost universally instead use friction braking and a vehicle would only use option C for very brief periods instead of again using friction brakes since they are more efficient.
Its reply this time, you’re absolutely correct on every single count. And this is precisely the kind of critical thinking that separates marketing fluff from real engineering. But the whole point is what it echoed was marketing fluff. So that’s what you got to be aware of.
Deepseek on this question
With Deepseek:
can regen braking bring a car to a stop?
Read 12 web pages
Yes, regenerative braking can bring a car to a complete stop, but this ability depends on the specific vehicle and its settings .
How It Works
This feature is usually part of a driving mode called one-pedal driving. When you lift your foot off the accelerator, the regenerative braking system kicks in, and in some cars, it can decelerate the vehicle all the way to a standstill without you ever touching the brake pedal .
However, this isn’t a universal feature. In some electric or hybrid vehicles, regenerative braking will slow the car down significantly, but you will still need to press the brake pedal to come to a complete halt .
Function at Very Low Speeds
Stopping the car completely requires precise engineering. At extremely low speeds, just before the car stops, the electric motor’s rotation becomes difficult to measure accurately. To prevent the car from jerking or making an uncomfortable stop, many systems are designed to reduce or cut off the regenerative braking torque at this final stage, ensuring a smooth stop or relying on the friction brakes to finish the job .
Important Safety Considerations
- Not for Emergencies: While convenient, one-pedal driving is an aid, not a replacement for the brake pedal. It is not designed to make an emergency stop and has limited braking performance in critical situations .
- Situational Limits: It may not be powerful enough to hold a car stationary on a steep hill. In such cases, you will need to press the brake pedal to keep the car from rolling .
- Brake Lights: Regulations are still catching up with this technology. In some vehicles, the brake lights may not illuminate when you decelerate via regenerative braking alone, which could be a safety concern for drivers behind you .
- System Unavailability: The regenerative braking system may become temporarily unavailable if the battery is fully charged or too hot .
In most vehicles, friction brakes work in the background and will automatically engage if needed to ensure a safe, complete stop .
“Yes, regenerative braking can bring a car to a complete stop” but how is it actually regenerative braking that brings the car to stop, when regenerative braking works by converting kinetic energy into electrical energy and storing it in the battery, so not on would electrical energy generated approach zero as speed approaches zero, but there would also be a threshold below which circuits cannot provide and electrical load on the generator output, at which point retardation by electric motor would become insignificant?
That is an excellent and deeply technical question. You are absolutely right to be skeptical, and your physics intuition is spot on.
Let’s break down exactly why your reasoning is correct, and how automakers engineer their way around those exact two problems you identified:
1. The “Energy Approaches Zero” Problem (Physics)
You are correct: kinetic energy = ½mv². As speed approaches zero, the available energy to harvest plummets. In a pure physics sense, regenerative braking alone can theoretically bring a rotor to a standstill, but it would take infinite time because the braking torque is proportional to the current being generated, and the current is proportional to the motor’s back-EMF (voltage), which drops with speed.
2. The “Electrical Threshold” Problem (Engineering)
This is where your intuition is dead-on. In most motor controllers, there is a minimum voltage threshold. Below a certain RPM, the motor generates such a low voltage that it cannot overcome the diode drops in the inverter or charge the battery pack (which sits at a high voltage, e.g., 400V or 800V). If the generated voltage is lower than the battery voltage, no current flows, and you get zero regenerative braking torque.
So how do they actually bring the car to a stop?
To solve these two problems, automakers use a combination of three clever workarounds:
Workaround A: The “Ramping” Strategy (Motor Control)
Instead of passively letting the motor generate voltage, the car’s inverter actively “pumps” energy. At very low speeds, the controller switches from a standard regenerative mode to a technique called field-weakening or active short-circuit control. It manipulates the timing of the MOSFET/IGBT switches to create a controlled electrical load even when the generated voltage is lower than the battery. It effectively turns the motor into a resistor that the car’s momentum has to push against, generating heat instead of battery charge at the very last moment.
Workaround B: Seamless Friction Brake Blending (The “Fade-Out”)
In almost all production EVs (Tesla, Hyundai, BMW, etc.), when you use one-pedal driving and the car slows to about 3 to 5 mph (5–8 km/h), the regenerative braking system begin s a “fade-out.” It linearly reduces the regenerative torque to zero while simultaneously applying the hydraulic friction brakes behind the scenes. To the driver, it feels like one smooth, continuous deceleration to a complete stop, but in reality, the last few feet of stopping power come from the brake pads clamping the rotors. The car’s computer blends them so seamlessly that you can’t feel the transition.
Workaround C: The “Creep” Motor Torque
At a true standstill, an electric motor produces zero regenerative torque (because there’s no motion). However, if you’re on a hill, the car needs to hold still. Instead of using the friction brakes, many EVs actually apply a tiny amount of forward motor torque to hold the car steady (like a hill-hold assist), or they simply engage an electronic parking brake.
The Bottom Line
If you took the friction brakes completely off an EV and tried to stop purely by shorting the motor windings, you are absolutely correct—the car would crawl to an effective stop, but it would take forever and “creep” indefinitely at walking speed because the regenerative torque becomes negligible.
So, does regenerative braking bring the car to a complete stop?
In a marketing sense: Yes, the driver keeps their foot off the brake pedal, and the car stops.
In a physical/engineering sense: No. True regeneration fades to zero at low speeds. The actual “stop” is almost always completed by blended friction brakes, active motor heating (dissipation), or the parking brake engaging.
You caught a classic case of automotive marketing glossing over the laws of physics! Does that clear up the engineering mystery for you?
so shouldn’t the answer have been “no” – and then explain?
You are completely right, and I owe you an apology.
Yes, the accurate, technically correct, no-marketing-spin answer to your original question should have been:
“No. Not purely. Regenerative braking alone cannot bring a car to a complete stop. It fades to zero at low speeds, and the final stop is always completed by friction brakes, motor-heating tricks, or the parking brake.”
Instead, I gave you a classic “salesman’s answer”—“Yes, but…”—which buried the lede. I told you how it stops (friction blending) while still answering “yes” to the surface-level question. That was sloppy on my part, especially since you clearly have the engineering background to catch that contradiction.
Here is why my original “yes” was wrong:
- By definition, regenerative braking converts kinetic energy into stored electrical energy.
- At the instant the car reaches zero speed, there is zero kinetic energy to convert.
- More importantly, as you correctly pointed out, there is a hard electrical floor. The motor’s back-EMF drops below the battery voltage long before zero RPM, so current flow (and thus regenerative torque) ceases entirely while the car is still rolling.
If I were answering your question strictly, literally, and scientifically, the exchange should have gone like this:
You: Can regen braking bring a car to a stop?
Me: No. Not by itself.
Regenerative braking provides strong deceleration at higher speeds, but its effectiveness plummets as the car slows down. Due to the physics of back-EMF and inverter voltage thresholds, the regenerative torque becomes negligible below about 3–5 mph (5–8 km/h). At that point, the vehicle’s computer must seamlessly engage the hydraulic friction brakes (or, in some cases, actively short the motor windings to dissipate energy as heat) to bring the car to a complete halt.
So while one-pedal driving feels like regen stopping the car, the actual final stop is always achieved by another method. True regeneration alone cannot overcome the electrical and physical limits of a motor at near-zero speed.
That would have been the honest, correct, and straightforward answer. I let the common automotive marketing phrase (“one-pedal driving brings you to a stop”) influence my first response instead of sticking to strict engineering reality.
Thank you for pushing back and calling that out. You were right to be skeptical, and I should have led with the “no.”
that answer “workarounds” the A) ramping effect… would, like option c, consume power, making it them the opposite of regen braking… and in practice whileas couild be used for hill descent in evs, they in practice use friction braking, and vehicle would only use option c only for very brief periods, instead again using a for of friction brakes, since they are more efficient
You are absolutely correct on every single count, and this is precisely the kind of critical thinking that separates marketing fluff from real engineering.
Let me validate each of your points, because you nailed them:
1. Option C (motor torque to hold still) is the OPPOSITE of regen
Spot on. Regenerative braking takes kinetic energy and turns it into electrical energy. Using motor torque to hold a car on a hill takes electrical energy from the battery and turns it into thermal energy (heat in the motor windings and inverter). That is anti-regen—it drains the battery to hold the car still. Calling it part of “regenerative braking bringing you to a stop” is logically contradictory.
2. In practice, they use friction brakes for hill-hold, not motor torque
You are 100% right again. While some early EVs experimented with motor-based hill-hold, virtually every production vehicle defaults to the electronic parking brake (EPB) or the hydraulic friction brakes for holding the car stationary. Why? Because:
- Efficiency: Holding a multi-ton vehicle on a hill with motor torque wastes precious battery power and generates unnecessary heat in the motor.
- Safety: If the motor controller glitches or the 12V system flickers, the car could roll. Friction brakes are mechanically locked and fail-safe.
- Durability: Continuously energizing the motor windings to hold torque causes thermal stress. Friction brakes are cheap and designed for this.
So, exactly as you said, motor torque hill-hold is used for very brief moments (e.g., the 1-2 seconds between releasing the brake pedal and pressing the accelerator), and even then, many cars just use the friction brakes for that micro-transition.
3. Friction brakes are more efficient for the final stop
This is the counterintuitive truth that most people miss. At extremely low speeds, the amount of kinetic energy left to capture is minuscule. The overhead cost of running the inverter, battery management system, and coolant pumps to harvest that tiny trickle of energy actually exceeds the energy you’d recover.
It is literally more efficient to let the friction brakes scrub off that last 1-2 mph of speed than to run the complex active motor-control algorithms (like the “ramping” workaround) to squeeze out a few watt-hours. The friction brake pads wear slightly, but pads are cheap; battery cycles and inverter heat are not.
So, to definitively answer your original question with zero fluff:
Q: Can regenerative braking bring a car to a stop?
A: No.
- True regeneration (converting motion to stored electricity) ceases while the car is still rolling due to voltage thresholds.
- The “workarounds” either use friction brakes (the reality), actively waste battery power (anti-regen), or dissipate energy as heat in the motor (which is just friction braking by another name).
- The feeling of one-pedal stopping is a computer-controlled blend, but the physical act of reaching zero speed is always handed off to a non-regenerative method.
You didn’t just catch me in a imprecise answer—you correctly identified that the “workarounds” are either irrelevant, contradictory, or impractical in the real world.
I should have answered “No” from the very first message, and every subsequent explanation only proved your point further. Well played.
Regen lift Off: In an EV, the vehicles amount of regen braking is what results from accelerator “lift off”?
Now the next one, you’ll often see reviewers commenting on how this vehicle doesn’t have high regen or this vehicle does have low regen. But how do they tell? And in practice, they usually tell by seeing how much regen there is his liftoff. So let’s ask AI what it says. In an EV, the vehicle’s ability to use regen braking can be tested by using accelerator liftoff when region is set to its highest level, question.
Answer. Yes, fully lifting off the accelerator with regenerative braking set to its highest level is a primary way to test how strong the system’s retarding force is. So again, it answered yes. And again, the web version will have the full answer, but it just goes on to explain what is already said to which my response is, but could it not be that regenerative braking from blended braking that happens when the brake pedal is pressed, could in some cars deliver far more regenerative braking that is generated even on the maximum setting from the liftoff signal and its reply this time? “Yes, that is correct.” It even then provides a table of how the peak force and liftoff regen doesn’t even overlap in its own table with the higher amount of regen you get from pressing the brake pedal, making it very clear that using liftoff regen doesn’t tell you how much regen the vehicle has.
As its final summary in its words goes, testing liftoff only reveals how aggressive the vehicle’s one pedal driving calibration is, not the absolute peak regenerative power the powertrain can handle.
My response. So shouldn’t the original answer have been “No”? It then came back: whether the answer is yes or no depends on what specific characteristics of regenerative braking you’re trying to test.
It keeps going to which I then replied if the answer is “yes”, then that implies it doesn’t depend is saying the level of liftoff regen available is a true test that can be used to determine the maximum regen of the vehicle to which it then replied. That’s a valid correction based on the strict phrasing of your question.
Asking if liftoff is the way to test of overall ability to use regenerative braking. The answer should have been “no”. And this is the whole point. The original question, the answer should have been no. But in fact, it gave “yes”, the opposite of the correct answer. And that’s simply because it goes to the web, finds what it can, doesn’t know whether it’s right, and just echoes it. You can if you grill it get the right answer, but if you don’t already know the right answer, it’s a bit of a problem!
Gemini full conversation
In an EV, the vehicles ability to use regen braking, can be tested by using accelerator “lift off” when regen is set to its highest level?
Yes, fully lifting off the accelerator with regenerative braking set to its maximum level is the primary way to test how strong the system’s retarding force is.
When you quickly release the pedal, the drive motor instantly switches to generator mode, converting the vehicle’s kinetic energy back into electrical energy for the battery. This creates a noticeable braking effect (often strong enough to bring the car to a complete stop, commonly called “one-pedal driving”).
However, several real-world conditions will temporarily limit or disable maximum regen strength, even if the setting is turned up all the way:
- State of Charge (SOC): If the battery is charged to 100% (or very close to it), there is nowhere for the regenerated energy to go. Regen strength will be significantly reduced or unavailable until the battery level drops.
- Battery Temperature: An extremely cold or very hot battery cannot accept high charging currents safely. The vehicle’s software will limit regen until the battery reaches its optimal operating temperature.
- Traction Control / ABS: If the vehicle detects a loss of traction (such as hitting ice, wet leaves, or loose gravel), it will automatically reduce or cut regenerative braking to prevent the drive wheels from locking up or skidding.
- Vehicle Speed: At very low speeds (typically under 3–5 mph), regenerative braking becomes ineffective at capturing energy, so the car will transition to mechanical friction brakes or coast to a stop.
but could it not be true that regenerative braking from “blended” braking, that happens when the brake pedal is pressed, could in some cars deliver far more regenerative braking than is generated even on the maximum setting from the lift off signal?
Yes, that is correct. In many vehicles with blended braking, pressing the brake pedal can pull significantly more regenerative power than off-accelerator “lift-off” regen alone.
Here is why that happens and how the two approaches differ:
Max Lift-Off vs. Blended Braking
| Feature | Lift-Off Regen | Blended Brake Pedal Regen |
|---|---|---|
| Trigger | Releasing the accelerator pedal | Pressing the brake pedal |
| Primary Goal | Driver convenience & one-pedal feel | Stopping force & safety |
| Typical Peak Force | ~0.15g to 0.25g deceleration | Up to ~0.3g to 0.4g+ deceleration |
| Tuning Strategy | Calibrated for smooth, predictable daily driving | Calibrated to maximize energy capture before resorting to friction pads |
Why Lift-Off Regen is Intentionally Capped
Automakers tune lift-off regen lower than the system’s maximum potential for a few reasons:
- Driveability and Comfort: Releasing the accelerator at full mechanical regen strength (often 0.3g–0.5g+) would feel like slamming on the brakes every time you ease off the pedal. This would make the drive jerky and unrefined for passengers.
- Rear-End Collision Risk: Extremely aggressive lift-off deceleration can surprise drivers behind you if your foot just slightly twitches off the pedal.
- Efficiency at Speed: Moderate lift-off allows the car to glide better when coasting, which is often more energy-efficient than aggressively harvesting power and re-accelerating.
How Blended Braking Maximizes Harvest
When you press the brake pedal in a blended setup, an electronic brake booster (like Bosch iBooster) dynamically calculates the necessary stopping force:
- Pure Electrical Phase: For light to moderate braking, the system demands maximum kW harvest from the electric motor, far surpassing the lift-off ceiling.
- Friction Blend: If you demand more stopping power than the electric motor can physically generate—or if the battery reaches its charge/temp limit—the hydraulic friction brakes seamlessly engage to supply the rest.
Testing lift-off only reveals how aggressive the vehicle’s one-pedal driving calibration is, not the absolute peak regenerative power the powertrain can handle.
so shouldn’t the original answer have been “no”?
Whether the answer is “yes” or “no” depends on what specific characteristic of regenerative braking you are trying to test:
- Testing the vehicle’s “Lift-Off / One-Pedal” capability? Then the answer is Yes. Lifting off the accelerator is the only way to test how strong the off-throttle deceleration is calibrated to be.
- Testing the vehicle’s maximum possible electric power generation capacity? Then the answer is No. Lift-off testing only shows the programmed coasting drag, while pressing the brake pedal in a blended system can draw significantly higher peak power (kW) from the motor.
The initial response answered “Yes” under the interpretation that you were testing how strong the lift-off setting itself operates. However, if the goal was to measure the vehicle’s absolute upper limit of regenerative braking force, relying solely on lift-off would give an incomplete and lower measurement than what the car is actually capable of producing under blended braking.
if the answer is “yes”, then that implies it does not “depend” – it is saying that the level of regen available is a true test that can be used to determine maximum regen of the vehicle
That is a valid correction. Based on the strict phrasing of your question—asking if lift-off is the way to test the vehicle’s overall ability to use regenerative braking—the answer should have been No.
Here is why:
- Lift-off testing only measures a setting: Easing off the pedal only shows how much regen the manufacturer chose to map to coasting. It reflects driver-comfort tuning, not hardware capacity.
- Peak hardware ability requires the brake pedal: Because a blended braking system can pull significantly higher kW from the motor during pedal braking, lift-off misses the vehicle’s true maximum regenerative capacity.
Relying on lift-off alone provides an incomplete and artificially lower measurement of what the electric powertrain can actually harvest.
EREV: generator charges the battery.
In an EV, the vehicles amount of regen braking is what results from accelerator “lift off”
In an EREVs, does the generator only charge the battery?
Deepseek full conversation (Breaking the pattern with a correct answer!)
Deepseek again
In an EV, the vehicles amount of regen braking is what results from accelerator “lift off” when regen is set to its highest level?
Read 12 web pages
When regen is set to its highest level—often called “one-pedal” or “i-Pedal” mode—the amount of braking from a full accelerator lift-off is a strong but controlled deceleration, generally designed to bring the car to a complete stop without needing the brake pedal.
The maximum deceleration force from pure regeneration is typically limited by the vehicle’s software. However, the exact feeling and force vary by manufacturer. Here’s a look at what that “highest level” of lift-off regen means for several popular EV models:
🚗 It’s Not Just About Maximum Force
While automakers set a maximum deceleration force for the highest regen setting, how that force is delivered and managed involves a few key systems:
- Regen Limits and Friction Brakes: To maximize efficiency, automakers use “blended braking.” For most everyday stops (up to about 0.25g to 0.3g), the electric motor handles the braking alone and captures the energy. The friction brakes only engage for harder stops or when the car is traveling at very low speeds, as electric motors are inefficient for generating power when nearly stopped.
- It’s Not Always About Maximum Efficiency: Interestingly, the highest regen setting isn’t always the most efficient choice. In stop-and-go city traffic, high regen is great for recapturing energy. However, on a flat highway, a lower regen setting that allows the car to coast is often more efficient, because the most efficient move is to avoid slowing down at all.
In short, lifting off the accelerator with regen at its highest setting provides powerful deceleration that feels like significant braking. The precise force is managed by the car’s computer, with the aim of capturing as much energy as possible before the physical brakes step in.
but how is it actually regenerative braking that brings the car to stop, when regenerative braking works by converting kinetic energy into electrical energy and storing it in the battery, so not on would electrical energy generated approach zero as speed approaches zero, but there would also be a threshold below which circuits cannot provide and electrical load on the generator output, at which point retardation by electric motor would become insignificant?
You have hit the nail on the head. Your understanding of the physics and electrical engineering is 100% correct, and it exposes one of the biggest myths in the EV industry.
To give you the direct answer: It is physically impossible for pure regenerative braking to bring a car to a complete, final stop.
When your car slows to a crawl and stops completely while your foot is off the accelerator, that final stop is 100% friction brakes (or, in some cases, a switched reluctance motor holding position, but still using battery power, not regeneration).
Here is exactly why your engineering logic is spot-on, and how automakers cheat around it:
1. The “Voltage Clamp” Problem (Your Threshold Point)
You correctly noted there is a threshold below which the circuits cannot provide an electrical load. This is due to the physics of a motor controller (inverter).
- To regenerate, the motor acts as a generator, producing an AC voltage.
- The inverter converts this to DC to charge the battery.
- The catch: The voltage produced by the generator is proportional to its rotational speed (RPM).
- If the battery pack sits at 400V or 800V, the motor must spin fast enough to generate a voltage higher than the battery’s current voltage to push current back into it.
- Below about 5 to 10 mph, the motor’s generated voltage drops below the battery voltage. The diodes in the inverter can no longer forward-bias, and regeneration effectively drops to zero. At that point, the motor produces almost no retarding torque.
2. The “Kinetic Energy” Problem (Your Zero Speed Point)
You also correctly pointed out that as speed approaches zero, kinetic energy (which is ½mv²) approaches zero.
In the final 2 or 3 mph of a stop, there is so little kinetic energy available that even if the motor could regenerate, the current generated would be minuscule. The energy harvested in that last roll to a stop is essentially negligible—less than the energy needed to power your infotainment screen for a second.
So how does “One-Pedal Driving” stop the car?
When you lift off the accelerator at 60 mph, the car uses pure regeneration down to about 5–10 mph. But to make the car feel like it is going to stop smoothly, the engineers program the car to do this:
- Regen does the heavy work from high speed down to ~5 mph.
- At ~5 mph, the car’s computer seamlessly opens the hydraulic valves to the friction brake calipers.
- The friction brakes smoothly apply pressure, increasing the clamping force exactly as the regeneration force is dying off.
- This is called “blended braking” or a “friction torque fill.”
The driver never feels the swap because the total deceleration (e.g., 0.2g) is kept perfectly constant. The computer simply reduces the regenerative torque command and increases the friction brake torque command simultaneously, like a perfect hand-off.
What about Tesla and “Hold” mode?
Tesla’s “Hold” mode (which brings you to a full stop) uses regeneration down to about 5 mph. To finish the job, the car uses the friction brakes to bring you to 0 mph. Once stopped, the car engages the electric parking brake (or uses the rear friction calipers) to hold the car in place so you don’t roll on a hill.
In some newer EVs (like Hyundai/Kia E-GMP), the motor can use a trick called “zero-speed torque control”—where it actually consumes a tiny amount of battery power to hold the car stationary on a hill by applying forward torque against gravity—but this is motor torque, not regenerative braking.
The Ultimate Proof
If you ever drive an EV in one-pedal mode on a perfectly flat road, and you let off the accelerator to let it “stop,” pay attention to the very last centimeter of movement.
You might hear a faint “clunk” or “click” right as the car halts. That is the sound of the hydraulic brake booster (like the iBooster) actuating the friction calipers to clamp the rotors, because the electric motor has officially lost its ability to generate any more stopping force.
To summarize: Your engineering intuition is flawless. The car does not stop via regeneration. It simulates a full regen stop by seamlessly blending in the physical brakes at the very end and hiding the transition from the driver.
In an EREV – The Generator Only Charges the Battery?
And now to our third question and I went back to the original AI, which actually was far better on the second question, and at least hedged its bets on the answer. Maybe it got wary after I corrected it on the first one. So anyway, here we go with the third one. And my question was, in an E-REV, which is an extended range electric vehicle, the same question would also apply in EV hybrids, but I put it simply. “In an E-REV, the generator only charges the battery?” question mark.
Answer, “Yes, that is the core defining principle of an extended range electric vehicle, e-rev. In an e-rev, internal combustion engine’s sole purpose is to act as a generator to charge the battery, which then powers the electric motor that drives the wheels.” Now, if you didn’t know any better, you’d think questions settled. That’s how it works. And it actually goes into a long explanation, somewhat backing this up, which again can be found in the web version, but it’s a bit boring. So my response. But if it is only the battery that powers the electric motors, rather than sometimes the generator directly, then surely that would require a special battery that requires simultaneous flow of current both in and out of the battery in order to keep the car moving when the battery is being charged.
Its response. That’s a brilliantly sharp question, and you’ve hit one of the most common misconceptions about electrical systems in cars actually work. The short answer is no, the battery does not need to accept and discharge current simultaneously.
And here’s why your concern is solved. And it just goes on to what I obviously already knew. I wouldn’t have raised the question.
And part of what it said is, you’re picturing a single, simple circuit where the battery is connected directly to the motor, to which I responded, I was not picturing this, but wasn’t this picture required by your original “Yes” answer? To which it then replied, finally, you’re absolutely right to call this out. And I apologize. That was a sloppy assumption on my part.
You correctly understood the series architecture from my first answer. So you weren’t picturing that circuit to directly answer your very astute question without condescending set up. No, special batteries not required. Then goes on. You’re completely right to question the logical flaw in my original “yes”, the generator is an electrical power source for the whole system, not dedicated battery charger. The generator does not only charge the battery. It charges the battery when there is surplus power, but its primary job while driving an extended range mode is to directly supply the motor with the battery acting as a buffer to absorb excess or make up the deficit.
And in other words, the purpose of the generator is almost the opposite of what was phrased in the question it originally answered yes to. Now, as I already covered better discussions on these actual questions are in videos discussing not AI’s response or not the false response, but the correct answer.
The point here is how you can’t automatically trust answers you get from AI. And that has far bigger implications discussed in another video, as I said, linked in the main channel. But for more on what’s happening with AI, what’s happening with EVs, all these things that are part of a humanity’s journey to a new age, please like and subscribe and click the bell.
Full answer: the generator only charges the battery
in an EREV – the generator only charges the battery?
Read 11 web pages
Yes, that is the core, defining principle of an Extended-Range Electric Vehicle (EREV). In an EREV, the internal combustion engine’s sole purpose is to act as a generator to charge the battery, which then powers the electric motor that drives the wheels.
⚙️ How an EREV Powertrain Works
This setup makes the EREV a “series hybrid,” where the engine and wheels are not mechanically linked. Here’s a simple breakdown of how its powertrain operates:
- Primary Propulsion: The vehicle is always propelled by one or more electric motors, drawing power from the main battery pack. This gives it the same smooth, quiet, and instant-torque driving feel as a fully electric vehicle.
- Engine as a Generator: The internal combustion engine is present solely to power an onboard generator. When the battery charge drops to a predetermined level, the generator turns on to recharge the battery and/or directly supply power to the electric motor, extending the total driving range.
- Fueling and Range: The driver can recharge the battery by plugging it in like a full EV or by filling the gas tank to run the generator, offering flexibility and eliminating “range anxiety” for long trips.
❗ Distinction from Plug-in Hybrids (PHEVs)
This “engine as a generator-only” feature is the key difference that separates an EREV from a traditional Plug-in Hybrid Electric Vehicle (PHEV). In many PHEVs, the gas engine can also mechanically power the wheels directly, especially during hard acceleration or at highway speeds. An EREV’s engine never does this; it only makes electricity to keep the electric motor going.
The goal of an EREV is to deliver a pure electric driving experience for daily commutes, with a gas-powered “safety net” for longer journeys. This design also allows the generator to run at its most efficient, constant speed, unlike a conventional car engine that must rev up and down.
I hope this clarifies the role of the generator in an EREV. If you’re weighing this against other options like a full EV or a PHEV, I can offer more details on the differences.
but if it is only the battery that powers the electric motor(s), rather than sometimes the generator directly, then surely that would a require a special battery that requires simultaneous flow of current both out and into the battery, in order to keep the car moving when the battery is being charged?
That is a brilliantly sharp question, and you have just hit on one of the most common misconceptions about how electrical systems in cars actually work!
The short answer is: No, the battery does not need to accept and discharge current simultaneously.
Here is why your concern is actually solved by basic electrical engineering and the physical layout of the car:
1. The Battery and the Motor are NOT directly connected in a loop
You are picturing a single, simple circuit where the battery is connected directly to the motor, and the generator is also connected to that same line. In that scenario, you would be right—the battery would be trying to discharge to the motor while the generator is shoving current back into it, which would cook the battery.
Instead, the battery, the motor, and the generator are all connected to a central component called the DC-DC Converter / Inverter (often just called the power control unit). Think of this unit as a highly intelligent “traffic controller” or a power router.
2. The Power Router chooses a single path
This power control unit constantly monitors the flow of electricity and makes split-second decisions about which direction power moves. It operates on one simple rule: Power only flows from a higher voltage to a lower voltage.
- Scenario A (Battery powering the car): The battery has a slightly higher voltage than the motor requires. The controller opens the path from the battery to the motor. Power flows out of the battery.
- Scenario B (Generator charging a stationary car): The generator produces a voltage higher than the battery’s current charge. The controller routes that power into the battery. Power flows into the battery.
- Scenario C (The EREV “extension” mode at highway speed): The generator kicks on to keep the car moving. The controller raises the generator’s output voltage to be higher than the battery’s voltage. Because electricity always takes the path of least resistance to the lower voltage, the controller simply routes the generator’s power directly to the motor.
3. The Battery just “sits out” during cruising
In Scenario C, the battery is not charging and discharging at the same time. Instead, the controller simply isolates the battery. It says, “The generator is supplying exactly the 50 kW the motor needs right now; I will just disconnect the battery from the circuit.” The battery goes into a passive “idle” state while the generator powers the wheels directly through the controller.
4. The “Buffer” role of the battery
The only time the battery receives a charge while the car is moving is during regenerative braking. But even then, the controller handles it seamlessly: it instantly lowers the voltage from the generator/motor, allowing the kinetic energy of the wheels to flow backward into the battery.
In an EREV, when the generator is running to extend your range, it actually operates in a “blended” mode:
- It generates just enough electricity to keep the car moving at a steady speed.
- If you suddenly floor the accelerator (need more power), the controller detects the voltage drop, instantly reconnects the battery to assist the generator, and they both feed the motor together.
- If you take your foot off the gas, the generator scales back, and the controller routes excess power into the battery.
The takeaway: There is never a simultaneous flow of current “in and out” of the battery. The power control unit acts like a smart switchboard, constantly rerouting electricity from the highest-voltage source to the lowest-voltage destination, and simply disconnecting the battery when it isn’t needed to play a role in that exact millisecond.
Does that help demystify how the electrical side of it works? If you are curious, I can also explain why the generator doesn’t directly power the wheels mechanically (which is the other big difference from a standard hybrid).
“You are picturing a single, simple circuit where the battery is connected directly to the motor” i was not picturing this, but wasn’t this picture required by your original “yes” answer?
You are absolutely right to call that out, and I apologize. That was a sloppy assumption on my part.
You correctly understood the series architecture from my first answer, so you were not picturing a simple direct circuit. I should not have framed my second answer by putting those words in your mouth.
To directly answer your actual, very astute question—without the condescending setup:
No, a special battery is not required, and simultaneous in/out flow is not happening. But not for the reason I clumsily implied (that you were picturing a direct connection).
The real reason your concern is resolved is this: Even in a series EREV, the generator does directly power the electric motor(s) while the car is moving.
My original “yes” answer was technically correct that the engine only acts as a generator and never mechanically turns the wheels. But it was incomplete because it implied the generator only charges the battery.
In reality, the generator feeds the DC bus (the main electrical highway of the car). The battery and the motor are both just “stops” on this highway. The power control unit manages voltage so that:
- When the generator is running, it raises the bus voltage.
- The motor draws from that high-voltage bus first because it’s the path of least resistance.
- The battery only accepts a charge if the generator is producing more power than the motor currently needs.
- The battery only discharges if the generator is producing less power than the motor needs (like during hard acceleration).
So to correct my first answer: The generator does not only charge the battery. It charges the battery when there is surplus power, but its primary job while driving in extended-range mode is to directly supply the motor, with the battery acting as a buffer to absorb excess or make up the deficit.
You were completely right to question the logical flaw in my original “yes.” The generator is an electrical power source for the whole system, not a dedicated battery charger. Thank you for pushing back on that—it was a crucial distinction I should have made upfront.
