5 ms·

To some extent, but not really. Effectiveness of regenerative braking depends on having an extremely large battery that can sink enough current to stop the car

by ajross 1y ago

To some extent, but not really. Effectiveness of regenerative braking depends on having an extremely large battery that can sink enough current to stop the car. An EV can do that, hybrids at best help the brakes out some. You just can't charge the battery fast enough doing anything but a very slow rolling stop. My model Y can effect a very reasonable stop in traffic without touching the brake pedal except to hold the car at the end.

jeffbee 1y ago
In normal driving hybrid regen is more than enough to do the job. Just look at the front wheels of any Prius. There are reasons all the Uber drivers choose the Prius.
dyselon 1y ago
We finally gave up our Prius after 12 years, and we never changed the brakes once. The brakes were just peeking into the yellow on its last service upgrade. I was really impressed with how well the "normal" hybrid could take advantage of regenerative breaking, honestly.
- Helmut10001 1y ago
  I first changed the brakes on my Mitsubishi Space Star (combustion) after 13 years. It is a small car, less than 1000kg, so there is little for the brakes to do. If we produced more percentage of small cars, many environmental risks would be reduced. And btw.: The tires are now 19 years old and still good (less weight, less abrasion!).
  - Tempest1981 1y ago
    Rubber degrades with UV exposure, even if the tread depth is ok. Be careful, esp at higher speeds.
  - deleted 1y ago
    [deleted]
  - lazide 1y ago
    Beware of dry rot. Rubber that old is likely not in as good shape as it might appear, and could fail catastrophically in the right conditions.
  - jajko 1y ago
    That's not OK by any means, you don't have mandatory periodical technical inspections? This would fail immediately in any half-decent country. An example - wife's older Seat has 6 years old winter tires which were given for free when buying it second hand a year ago. Technician just told us even those are beyond acceptable here in Switzerland and we need to change them before next inspection. Your very old tires makes you a serious threat on the road while completely oblivious about this fact... not cool, please change them if you drive on public roads, if not for you just for the sake of others.
    - Helmut10001 1y ago
      We are in Germany, which has the highest inspection standards. The tires have passed every inspection. They look like new, but I will still replace them soon, just in case. I am writing this because most people cannot imagine that a 900 kg car puts very little pressure on tires, so they are hardly used.
  - pkolaczk 1y ago
    Seriously, you should not use tires older than 10 years. They degrade over time.
    - potato3732842 1y ago
      Time based degradation is mostly a factor of exposure to the sun and the weather. I just trashed some 15yo Firestones last month, after wearing them completely bald of course.
Swizec 1y ago
> My model Y can effect a very reasonable stop in traffic without touching the brake pedal except to hold the car at the end. My manual car could do this 20 years ago. My fully ICE motorcycle can do it today. I know engine braking is cool but it’s not some amazing new thing only EVs can do. Altho granted it only produces heat and noise in petrol vehicles. But it also makes your heart sing so that’s nice
- shmoe 1y ago
  The difference is neither of those generates gasoline on an ICE vehicle.
  - tzs 1y ago
    Yup. For example on a round trip today in me EV (2025 Hyundai Kona) on the out here are the stats: 2 kWh for the drivetrain 809 Wh regenerated On the way home: 2 kWh for the drivetrain 547 Wh regenerated For the round trip that's 33% less energy use than if the car did not have regenerative braking. I'm mostly happy about that but there is one thing that annoys me. 33% is close to how much a kilometer is shorter than a mile (38%). Why the fuck would I care that these two numbers are that close? It is because of a mystery in the Hyundai app. When you look up the trip details for an EV trip it gives you mileage, duration, and energy use (drivetrain, climate, accessories) and regeneration. The mileage is substantially less than what the car shows. For example for the aforementioned trip home that trip odometer shows 8.0 miles but the Hyundai app shows 5 miles. The car odometer has the correct distance. There are two theories to explain this. 1. The app is showing how many miles worth of energy you used rather than your actual trip mileage. All the other data it shows (except for the duration) is energy related. For my 8.0 mile trip I got 3 miles worth of the energy the drivetrain used back via regeneration, so I only actually paid for 5 miles worth of electricity. Based on the Wh given it should actually be 5.4 miles, but the app only displays integer mileage so 5 it is. 2. It's a botched unit conversion. E.g., the car uploads the data in miles but the expects the data to be in km, so it is doing a conversion. That would turn the 8.0 into 5.0, which would be 5 in the app and so matches what theory #1 predicts. I've checked several of my trips and they have always happened to have the right amount of regeneration so that the two theories match due to the app only showing an integer mileage. I did a test today to try to tell them apart. I changed the car's settings to km and took a trip. The idea was if the car had been uploading in miles that would hopefully change it to upload in km, matching the app's expectation, and so the miles shown in the app would match the actual miles of the trip if theory #2 was correct, and show the regeneration corrected miles if theory #1 was correct. The result was that the app still showed miles consistent with theory #1. So mystery solved, right? Maybe not. When the car was set to miles everything showed in miles. Speedometer, odometers, efficiency (mi/kWh), speed limits it read from traffic signs, and speed limits it gets from the map data when using navigation on highways. I expected than when I switched it to km all of those would be in km, and I would not see miles anywhere. Also, I expected that when it saw a speed limit sign that said say 60 it would interpret that as 60 km/hr. What actually happened is that miles mostly did go away, except on the speedometer it added a smaller mi/hr display under the km/hr display. For the traffic signs it still knew they were in mi/hr and it converted them, so when I got on the freeway as soon as I passed the sign that said 60 the speed limit sign shown on the instrument cluster said 97, and the red dot on the speedometer showing the current limit was placed in the right place. That suggests that the car knows it is in a country that uses miles, and doesn't just go by whatever the units setting in the setup screen is set to. It could be that in miles countries the car also uploads in miles all the time, and so switching the units setting to km would not change the results if theory #2 was true. Now my plan is to find a big parking lot that is mostly empty overnight, such at a Walmart or Home Depot or a mall, go there and turn the car off and then back on which starts a new trip, set regeneration to 0 which turns off automatic regeneration on the accelerator so the car only regenerates when you use the brake pedal, and then drive around the parking lot for about 10 miles without using the brakes, then coast to a stop and turn the car off the end the trip. Then I'll turn it back on, drive home, and check the trip details in the app. If theory #1 is right then the miles in the app should match the odometer miles. If theory #2 is correct the app miles should still be 38% shorter than the odometer miles.
arnonejoe 1y ago
I test drove an EV and the regenerative braking was difficult to get used to. You have to constantly ride the gas pedal. I would buy an EV if it weren't for this feature.
- Rover222 1y ago
  You can toggle off regen braking on most EVs
- mrpippy 1y ago
  Some EVs allow different levels of regenerative braking to be selected. The Hyundai/Kia E-GMP-based cars have level 0-3 plus a 1-pedal mode, and also an "auto" mode that slows down more based on radar proximity to the car ahead.
- schmookeeg 1y ago
  We have owned 4 EVs and each allow you to configure the regen braking strength. You'll need another reason to not buy one.
  - apelapan 1y ago
    Tesla is a quite common EV brand. They do not allow configuring regen braking, except for the behaviour at stand-still. (They also don't do blending between friction brakes and regen, so the cars behaviour when letting of the accelerator is highly inconsistent depending on temperature and charge level). One of the reasons I long for the lease on my Model Y to end so I can replace it with a less stupid vehicle.
    - stavros 1y ago
      I agree with the general sentiment, but this isn't relevant in the context of making a purchasing decision. Simply buy another brand.
      - apelapan 1y ago
        I have learned my lesson on regen. Lots of people online (and offline, for that matter) told me that you'll get used to the Tesla behaviour in no time and not to worry about it feeling weird during the test drive. Many thousands kilometers later I hate it almost as much as at the start, so lack of regen configuration will be a dealbreaker next time I pick a new car.
tbrownaw 1y ago
> Effectiveness of regenerative braking depends on having an extremely large battery that can sink enough current to stop the car. An EV can do that, hybrids at best help the brakes out some. You just can't charge the battery fast enough doing anything but a very slow rolling stop. This seems a bit exaggerated. Staying regenerative-only does require sticking to about half or so of how fast I could stop, but so far that seems to work fine unless a light turns right in front of me or traffic acts up. Usually it says it gets high 90's or 100%, and it didn't go below 50% even when a stoplight did turn at exactly the wrong time. (2022 Ford Escape non-plug-in hybrid, recently bought used.)
- CraigJPerry 1y ago
  100% of possible system capacity to accept regenerative charge on a smaller battery system will be a smaller absolute number than 100% of possible on a larger battery. If you assume everything else is constant, motor, inverter, battery C-rating etc.
  - tbrownaw 1y ago
    The manual says it's energy recovered (ie, not something relative to system capacity), and this seems consistent with the other indicator that shows instantaneous braking power with a distinction between what the regenerative system is doing vs what (if anything) the traditional brakes are doing.
    - CraigJPerry 1y ago
      which car? i think the number you're referring to is relative to electrical system capacity. It's NOT relevant to overall (tyre, brake system & engine braking & regen braking) braking system performance since that's a dynamic value variable over many factors constantly.
  - Dylan16807 1y ago
    I'm not sure what you're arguing here. Bigger battery is more capacity sure. But their point was that even without a big battery they have enough capacity to get close to maximum effectiveness, contrary to ajross saying that a hybrid's capacity is "not really" effective and "at best" helps "some".
cyberax 1y ago
You can just waste energy on eddy currents, and then use the car's cooling system to conduct away the heat. After all, dynamic brakes on locomotives just dissipate the generated electricity using resistors. Hybrid makers just don't really care about that.
dotancohen 1y ago
If your Model Y is like my Model 3, then it seamlessly switches to friction breaking below 20 kph. That said, I'm at 110,000 km and the brakes look like new.
friendzis 1y ago
> You just can't charge the battery fast enough doing anything but a very slow rolling stop. And it's not a problem when you get used to regenerative-only braking distances, which are surprisingly long at highway speeds. It only becomes a problem when idiots thinking "the shorter the distance between first and last car, the smaller the traffic" start cutting you off when you leave enough distance for regenerative braking.

by ajross 1y ago

jeffbee 1y ago

In normal driving hybrid regen is more than enough to do the job. Just look at the front wheels of any Prius. There are reasons all the Uber drivers choose the Prius.

dyselon 1y ago

We finally gave up our Prius after 12 years, and we never changed the brakes once. The brakes were just peeking into the yellow on its last service upgrade. I was really impressed with how well the "normal" hybrid could take advantage of regenerative breaking, honestly.

Helmut10001 1y ago
I first changed the brakes on my Mitsubishi Space Star (combustion) after 13 years. It is a small car, less than 1000kg, so there is little for the brakes to do. If we produced more percentage of small cars, many environmental risks would be reduced. And btw.: The tires are now 19 years old and still good (less weight, less abrasion!).
- Tempest1981 1y ago
  Rubber degrades with UV exposure, even if the tread depth is ok. Be careful, esp at higher speeds.
- deleted 1y ago
  [deleted]
- lazide 1y ago
  Beware of dry rot. Rubber that old is likely not in as good shape as it might appear, and could fail catastrophically in the right conditions.
- jajko 1y ago
  That's not OK by any means, you don't have mandatory periodical technical inspections? This would fail immediately in any half-decent country. An example - wife's older Seat has 6 years old winter tires which were given for free when buying it second hand a year ago. Technician just told us even those are beyond acceptable here in Switzerland and we need to change them before next inspection. Your very old tires makes you a serious threat on the road while completely oblivious about this fact... not cool, please change them if you drive on public roads, if not for you just for the sake of others.
  - Helmut10001 1y ago
    We are in Germany, which has the highest inspection standards. The tires have passed every inspection. They look like new, but I will still replace them soon, just in case. I am writing this because most people cannot imagine that a 900 kg car puts very little pressure on tires, so they are hardly used.
- pkolaczk 1y ago
  Seriously, you should not use tires older than 10 years. They degrade over time.
  - potato3732842 1y ago
    Time based degradation is mostly a factor of exposure to the sun and the weather. I just trashed some 15yo Firestones last month, after wearing them completely bald of course.

Swizec 1y ago

> My model Y can effect a very reasonable stop in traffic without touching the brake pedal except to hold the car at the end. My manual car could do this 20 years ago. My fully ICE motorcycle can do it today. I know engine braking is cool but it’s not some amazing new thing only EVs can do. Altho granted it only produces heat and noise in petrol vehicles. But it also makes your heart sing so that’s nice

shmoe 1y ago
The difference is neither of those generates gasoline on an ICE vehicle.
- tzs 1y ago
  Yup. For example on a round trip today in me EV (2025 Hyundai Kona) on the out here are the stats: 2 kWh for the drivetrain 809 Wh regenerated On the way home: 2 kWh for the drivetrain 547 Wh regenerated For the round trip that's 33% less energy use than if the car did not have regenerative braking. I'm mostly happy about that but there is one thing that annoys me. 33% is close to how much a kilometer is shorter than a mile (38%). Why the fuck would I care that these two numbers are that close? It is because of a mystery in the Hyundai app. When you look up the trip details for an EV trip it gives you mileage, duration, and energy use (drivetrain, climate, accessories) and regeneration. The mileage is substantially less than what the car shows. For example for the aforementioned trip home that trip odometer shows 8.0 miles but the Hyundai app shows 5 miles. The car odometer has the correct distance. There are two theories to explain this. 1. The app is showing how many miles worth of energy you used rather than your actual trip mileage. All the other data it shows (except for the duration) is energy related. For my 8.0 mile trip I got 3 miles worth of the energy the drivetrain used back via regeneration, so I only actually paid for 5 miles worth of electricity. Based on the Wh given it should actually be 5.4 miles, but the app only displays integer mileage so 5 it is. 2. It's a botched unit conversion. E.g., the car uploads the data in miles but the expects the data to be in km, so it is doing a conversion. That would turn the 8.0 into 5.0, which would be 5 in the app and so matches what theory #1 predicts. I've checked several of my trips and they have always happened to have the right amount of regeneration so that the two theories match due to the app only showing an integer mileage. I did a test today to try to tell them apart. I changed the car's settings to km and took a trip. The idea was if the car had been uploading in miles that would hopefully change it to upload in km, matching the app's expectation, and so the miles shown in the app would match the actual miles of the trip if theory #2 was correct, and show the regeneration corrected miles if theory #1 was correct. The result was that the app still showed miles consistent with theory #1. So mystery solved, right? Maybe not. When the car was set to miles everything showed in miles. Speedometer, odometers, efficiency (mi/kWh), speed limits it read from traffic signs, and speed limits it gets from the map data when using navigation on highways. I expected than when I switched it to km all of those would be in km, and I would not see miles anywhere. Also, I expected that when it saw a speed limit sign that said say 60 it would interpret that as 60 km/hr. What actually happened is that miles mostly did go away, except on the speedometer it added a smaller mi/hr display under the km/hr display. For the traffic signs it still knew they were in mi/hr and it converted them, so when I got on the freeway as soon as I passed the sign that said 60 the speed limit sign shown on the instrument cluster said 97, and the red dot on the speedometer showing the current limit was placed in the right place. That suggests that the car knows it is in a country that uses miles, and doesn't just go by whatever the units setting in the setup screen is set to. It could be that in miles countries the car also uploads in miles all the time, and so switching the units setting to km would not change the results if theory #2 was true. Now my plan is to find a big parking lot that is mostly empty overnight, such at a Walmart or Home Depot or a mall, go there and turn the car off and then back on which starts a new trip, set regeneration to 0 which turns off automatic regeneration on the accelerator so the car only regenerates when you use the brake pedal, and then drive around the parking lot for about 10 miles without using the brakes, then coast to a stop and turn the car off the end the trip. Then I'll turn it back on, drive home, and check the trip details in the app. If theory #1 is right then the miles in the app should match the odometer miles. If theory #2 is correct the app miles should still be 38% shorter than the odometer miles.

arnonejoe 1y ago

I test drove an EV and the regenerative braking was difficult to get used to. You have to constantly ride the gas pedal. I would buy an EV if it weren't for this feature.

Rover222 1y ago
You can toggle off regen braking on most EVs
mrpippy 1y ago
Some EVs allow different levels of regenerative braking to be selected. The Hyundai/Kia E-GMP-based cars have level 0-3 plus a 1-pedal mode, and also an "auto" mode that slows down more based on radar proximity to the car ahead.
schmookeeg 1y ago
We have owned 4 EVs and each allow you to configure the regen braking strength. You'll need another reason to not buy one.
- apelapan 1y ago
  Tesla is a quite common EV brand. They do not allow configuring regen braking, except for the behaviour at stand-still. (They also don't do blending between friction brakes and regen, so the cars behaviour when letting of the accelerator is highly inconsistent depending on temperature and charge level). One of the reasons I long for the lease on my Model Y to end so I can replace it with a less stupid vehicle.
  - stavros 1y ago
    I agree with the general sentiment, but this isn't relevant in the context of making a purchasing decision. Simply buy another brand.
    - apelapan 1y ago
      I have learned my lesson on regen. Lots of people online (and offline, for that matter) told me that you'll get used to the Tesla behaviour in no time and not to worry about it feeling weird during the test drive. Many thousands kilometers later I hate it almost as much as at the start, so lack of regen configuration will be a dealbreaker next time I pick a new car.

tbrownaw 1y ago

> Effectiveness of regenerative braking depends on having an extremely large battery that can sink enough current to stop the car. An EV can do that, hybrids at best help the brakes out some. You just can't charge the battery fast enough doing anything but a very slow rolling stop. This seems a bit exaggerated. Staying regenerative-only does require sticking to about half or so of how fast I could stop, but so far that seems to work fine unless a light turns right in front of me or traffic acts up. Usually it says it gets high 90's or 100%, and it didn't go below 50% even when a stoplight did turn at exactly the wrong time. (2022 Ford Escape non-plug-in hybrid, recently bought used.)

CraigJPerry 1y ago
100% of possible system capacity to accept regenerative charge on a smaller battery system will be a smaller absolute number than 100% of possible on a larger battery. If you assume everything else is constant, motor, inverter, battery C-rating etc.
- tbrownaw 1y ago
  The manual says it's energy recovered (ie, not something relative to system capacity), and this seems consistent with the other indicator that shows instantaneous braking power with a distinction between what the regenerative system is doing vs what (if anything) the traditional brakes are doing.
  - CraigJPerry 1y ago
    which car? i think the number you're referring to is relative to electrical system capacity. It's NOT relevant to overall (tyre, brake system & engine braking & regen braking) braking system performance since that's a dynamic value variable over many factors constantly.
- Dylan16807 1y ago
  I'm not sure what you're arguing here. Bigger battery is more capacity sure. But their point was that even without a big battery they have enough capacity to get close to maximum effectiveness, contrary to ajross saying that a hybrid's capacity is "not really" effective and "at best" helps "some".

cyberax 1y ago

You can just waste energy on eddy currents, and then use the car's cooling system to conduct away the heat. After all, dynamic brakes on locomotives just dissipate the generated electricity using resistors. Hybrid makers just don't really care about that.

dotancohen 1y ago

If your Model Y is like my Model 3, then it seamlessly switches to friction breaking below 20 kph. That said, I'm at 110,000 km and the brakes look like new.

friendzis 1y ago

> You just can't charge the battery fast enough doing anything but a very slow rolling stop. And it's not a problem when you get used to regenerative-only braking distances, which are surprisingly long at highway speeds. It only becomes a problem when idiots thinking "the shorter the distance between first and last car, the smaller the traffic" start cutting you off when you leave enough distance for regenerative braking.