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Model S Regenerative Braking is Different Than Hybrid Regen..Why?
- Thread starter Evbwcaer
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- Driving Dynamics Model S
HankLloydRight
No Roads
Search for "coasting in neutral"...
Roadshow: Downhill in neutral is illegal and dumb, and a lot of drivers do it - San Jose Mercury News
Roadshow: Downhill in neutral is illegal and dumb, and a lot of drivers do it - San Jose Mercury News
May be some of the disagreement and discussion here is a lack of understanding.
I have only driven one hybrid, the one I currently own. It has some (varied by situation) regen when the accelerator is released like the Tesla, AND it gives full regen when the brake pedal is lightly pressed.
Some have been concerned with the complexity this adds, but it literally is based off of the brake light switch -- brake lights on, full regen.
Full regen is probably not something you would want on a Tesla, but a simple system to significantly increase regen when the brake is pressed gives a little more control of regen.
No need for a discussion of which is "better." The brake regen is an addition to the system employed by Tesla, not a replacement for it.
I have only driven one hybrid, the one I currently own. It has some (varied by situation) regen when the accelerator is released like the Tesla, AND it gives full regen when the brake pedal is lightly pressed.
Some have been concerned with the complexity this adds, but it literally is based off of the brake light switch -- brake lights on, full regen.
Full regen is probably not something you would want on a Tesla, but a simple system to significantly increase regen when the brake is pressed gives a little more control of regen.
No need for a discussion of which is "better." The brake regen is an addition to the system employed by Tesla, not a replacement for it.
better is Tesla's method. no regen on brake, all on throttle lift-off
have driven Prius' and a Volt. 'bad' brake feeling in both. very odd and silly implementation. There is no question which is better. some may like the regen on brake
back OT:tongue:
Is it illegal to put a car (Model S) in reverse and coast forwards at a high speed?
Would you prefer your foot on the brake pedal, or on the accelerator, when you are rear-ended? Good safety feature. Also, as the car slows to a certain point the regenerative effect falls to such a low level that the car would never come to a complete stop without the addition of power to complete the process. Then, at full stop more power is required to hold position if there is any slope. Probably not the best use of limited energy.
HankLloydRight
No Roads
I don't know about anyone else, but there's a road that runs downhill near here, and if I'm coasting (full regen) down the hill, the regen will bring the car to a complete stop ON THE HILL, still facing downward.
NE hill vs SD hill?
The Leaf has variable regen which allows almost 1 pedal driving as long as you are not very aggressive. Older Leaf's varied but 2013 and later allow full regen when you lift the accelerator. Braking means friction braking right away with regen. The regen isn't full if the speed is low or it isn't set to max and so braking adds to that. Pretty seamless and leads to pretty good brake feel. The only noticeable issue is that when the battery is full or cold, you wind up pushing a bit more on the brake. To me, this only happens at 98% SOC - so pretty rare, in my neighborhood after a max charge.
Truly the best (IMO) is regen by paddles - like downshifting an ICE. You can max it out easily, you can coast easily. I'm not a huge fan of trying to perfectly feather the accelerator to get "zero". Coasting is ideal - depending on the type of environment you drive in, it can be pretty common and not disruptive. If I see a red light 1/4 mile out that is red and I am going 45, I want to coast. The light might turn green so I hate to start regen. But then at 1/8 mile (estimate) and it is still red, I want max regen.
The Leaf has variable regen which allows almost 1 pedal driving as long as you are not very aggressive. Older Leaf's varied but 2013 and later allow full regen when you lift the accelerator. Braking means friction braking right away with regen. The regen isn't full if the speed is low or it isn't set to max and so braking adds to that. Pretty seamless and leads to pretty good brake feel. The only noticeable issue is that when the battery is full or cold, you wind up pushing a bit more on the brake. To me, this only happens at 98% SOC - so pretty rare, in my neighborhood after a max charge.
Truly the best (IMO) is regen by paddles - like downshifting an ICE. You can max it out easily, you can coast easily. I'm not a huge fan of trying to perfectly feather the accelerator to get "zero". Coasting is ideal - depending on the type of environment you drive in, it can be pretty common and not disruptive. If I see a red light 1/4 mile out that is red and I am going 45, I want to coast. The light might turn green so I hate to start regen. But then at 1/8 mile (estimate) and it is still red, I want max regen.
HankLloydRight
No Roads
That's really interesting behavior and something I've never experienced in 34K miles of driving with my S set to Standard regen. Gotta go find me a hill and experiment. How steep is your hill, Hank?
I have driven an iMiev for 2 years and that has both options available:
1. If you put it in 'D' mode, it has Volt/Leaf style low regen on the 'go' pedal + regen on first portion of break pedal pressing.
2. If you put it in 'B' mode, it has max regen on the 'go' pedal (like the Tesla), although it still has regen on the break too.
IMHO, from a UI standpoint this is the best solution (although it adds engineering complexity). It allows regular ICE drivers to benefit from the regen, but you can also do the 1-pedal driving. I started out mostly driving in 'D' mode, because 'B' felt strange and it felt more difficult to keep the needle in the middle, than it was in 'D' for coasting. However, I gradually experimented more with 'B' and learned to drive that style and once you get used to it is more convenient because you don't need to shift you foot left-right so often. When I got my Tesla, it was completely natural to drive with the standard regen setting.
So, at the end the Tesla way is better, but the 'option' is good for gentle adaption.
That is counter to my experience. In my S with the Regen set to Standard the car takes a long time to come to a full stop on a level surface on regen alone. Any noticeable downward slope and the car won't stop. On anything that I would call a "hill" the car definitely will not come to a stop on regen alone.
My wording wasn't precise, of course it cannot add 'more' regen, but the break pedal does behave the same way as in 'D' in the sense, that light pressing does not result in mechanical breaking it will use regen only until you press the break harder. So the feeling / feedback of how the break works does not change between the modes. Which also means the breaking is somewhat different from the Tesla, because Tesla applies mechanical breaking even for a light pressure on the break pedal.
Exactly. It may be possible now with the D and the electric brakes. potential to capture add'l regen after the regen from lifting off the accel pedal -- with application of the brake pedal to make more electricity instead of making brake dust.
I'm certainly expecting that from Tesla. A P85D should be capable of about 220kW of regen above the critical speed, if the pack can take it (the 60kW the car permanently does on the rear motor, plus the front motor running at its 160ish kW maximum.) That's almost half of a full on panic stop, if I did my math right - and still less load on the cells than the Volt does every day (less than 3C - the Volt's 60 kW limit is almost 4C.)
Even if Tesla doesn't want to exceed the supercharger limit, they could double the regen when the battery is in the range where it can take it - and with the new systems, seamlessly replace it with friction braking when the battery can't take the power.
Walter
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Just to clarify, I am pretty sure that currently regen braking is entirely controlled by the go pedal. Several automobile magazine articles early on praised this decision by Tesla as one providing the simplest, yet the best functional decision in terms of brake system feel and performance. The brake pedal is controlling hydraulic system only. It should be also noted, that once the go pedal is released, the regen is kept at maximum (according to the base speed of the motor, or more precisely, generator). The brake pedal is adding hydrailic braking on top of that.
I agree that for the D variants the regen will be increased substantially; in addition to adding front motor/generator regen, the rear axle regen can probably be increased as well. One additional limiting factor, on top of inverter throughput and ability of the battery accept current, would be rating of the motors. I do not know the continuous rating of the front motor, but continuous rating of the rear motor is 69kW.
I agree that for the D variants the regen will be increased substantially; in addition to adding front motor/generator regen, the rear axle regen can probably be increased as well. One additional limiting factor, on top of inverter throughput and ability of the battery accept current, would be rating of the motors. I do not know the continuous rating of the front motor, but continuous rating of the rear motor is 69kW.
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GaryREM
Member
That can't happen. Regen occurs when the motor is rotating and rapidly goes to zero as you approach low speed. Can't stop the car and there is no regen when car is stopped. Unless the brakes are being lightly applied, will not stop. If it does stop on downhill, something else is stopping it.
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