Does any manufacturer actually have a regenerative braking and charging system that the driver can modulate instantaneously via a brake pedal?
Without that capability I’ve always felt the charge-while-slowing systems give a false impression of a free lunch. Yes you get some juice for your battery, but by slowing the car down more rapidly than it would while properly coasting. You get the same energy outcome with no charging system just by coming off the power sooner and letting it coast further.
skydriller wrote:
who have a nice house with their own personal driveway that will have more than one car sat on it anyway
Doesn’t everybody 
As with everything else, it’s fundamentally a choice how you live. ATM I have 4 cars in my “driveway”, but could easily have 2 more without it being cramped at all. I live in a ordinary house like everyone else. Now, i could move to some larger city at some fancy downtown refurbished “district”, with a cafe’ at every corner, and zero parking space being nervous every night that some drunk youth wannabe hooligans vandalized my only car, but why?
Graham wrote:
Even if you don’t have a car, you depend on a lot of things that have to be moved by road and probably make use of taxis, buses, or you cycle on the road…
I’m trying hard to think of people I know who don’t have a car, ancient parents of friends in care homes etc. Two such non-drivers have passed on recently, leaving me with a count of one worldwide, an elderly aunt in Europe who pays no taxes of any kind.
My three car attached garage is occupied by two cars and four motorcycles. The rest of the fleet has to live elsewhere, mostly at my hangar. I don’t park cars on our driveway, it spoils the esthetics
Does any manufacturer actually have a regenerative braking and charging system that the driver can modulate instantaneously via a brake pedal?
Presumably somebody knows how this is actually done, but I suspect regen braking makes sense automatically only in the context of cruise control, to maintain the preset speed while going downhill. For most other scenarios the system would (mostly) apply the brakes, because (a) a car slows down pretty fast by itself anyway and (b) you would need a lot of magnetic torque to achieve enough braking torque for what one might call a common driving style. Then there is the question of transmission wear, if the motor/generator is a long way inboard. AFAIK no production electric car has motors inside the wheels, because the unsprung weight would be too great.
Silvaire wrote:
I’m trying hard to think of people I know who don’t have a car, ancient parents of friends in care homes etc.
Yes I can’t really think of any either. I guess it’s a city-living thing, the lifestyle that @LeSving mentions in his post.
Silvaire wrote:
an elderly aunt in Europe who pays no taxes of any kind.
You’re The Queen’s nephew? :-)
I suppose upon reflection she returns a bit of her state pension with VAT on retail purchases.
It all depends on the car.
There are two ways regen braking happens:
The Porsche Taycan is configured to have ‘lift-off’ regeneration comparable to a car with ‘normal’ transmission, and when you press the brake pedal it uses regen braking unless that does not deliver enough, then brakes in addition.
Tesla does not have that, it has strong ‘lift-off’ regeneration, and I normally drive without touching the brake pedal at all, although in the winter with a cold battery that does not work as regen is limited until the battery warms up, which it never seems to do fully. The brakes are just brakes. You can reduce the regen power, but it just means that the deceleration with the foot fully off the accelerator is lower.
I have no personal experience with other EVs.
Peter wrote:
Presumably somebody knows how this is actually done, but I suspect regen braking makes sense automatically only in the context of cruise control, to maintain the preset speed while going downhill. For most other scenarios the system would (mostly) apply the brakes, because you would need a lot of magnetic torque to achieve enough braking. Then there is the question of transmission wear, if the motor is a long way inboard. AFAIK no production electric car has motors inside the wheels, because the unsprung weight would be too great.
I think the KERS system in Formula 1 caused folks to get carried away over what might be possible for road cars, forgetting that motorsport by its very nature involves an awful lot of very heavy braking so there’s a huge amount of energy to be recovered. On the road your best strategy for improved efficiency is better anticipation, smoother driving and avoiding all that braking, and once you’ve done that there’s very little recoverable – so much so that it’s probably not worth the weight and complexity of the system.
Cobalt wrote:
You can reduce the regen power, but it just means that the deceleration with the foot fully off the accelerator is lower.
Indeed. Remove it completely and you can come off the power sooner and coast further, for the same net outcome.
Perhaps the lift-off regen systems are better suited to dense traffic environments where opportunities for coasting are limited.
Steve6443 wrote:
How will the car know that the coefficient of grip is lower?
How can it know before actually braking? But I guess you can adjust the distance to the car in front? Put it to max, and it will give you some peace of mind in the snow is my experience.
Graham wrote:
Does any manufacturer actually have a regenerative braking and charging system that the driver can modulate instantaneously via a brake pedal?Without that capability I’ve always felt the charge-while-slowing systems give a false impression of a free lunch. Yes you get some juice for your battery, but by slowing the car down more rapidly than it would while properly coasting. You get the same energy outcome with no charging system just by coming off the power sooner and letting it coast further.
That is different from manufacturer to manufacturer. VW do modulation, from a lot to zero. This is done, at least on the first gen electric cars from them, by using the “gear shift” lever sideways. Works very well. Most economical drive is manual and zero regeneration. Everything auto will apply regeneration downhill for instance. It will keep the speed, but it’s pretty uneconomical if you are driving on undulating roads. Then it is better to use the kinetic energy going downhill to get uphill again, varying the speed, but keeping the same average speed. Regeneration has an efficiency loss, so you lose some energy. Then when using that energy again, there is the efficiency loss again. So it is a double loss. It’s pretty high efficiency, but driving manually is better. The “downside” by doing it manually, varying the speed, is to keep the average speed at the speed limit, you will have to go considerably faster than the speed limit at places. Therefore also pretty obvious that the automation on the car won’t allow it, it can only be done manually.
My Mazda has this F1 gear shift things doing the same, from zero to a lot. I either drive in full auto, or manual and switch between them as needed. When in manual, I use the regen as a brake. In a Tesla 3 you have to take your eyes of the road, look right at the screen, swipe the screen left or right a couple of time, find the regen “button” which has only two modes, lots and a bit less (I’m not joking, it’s meant for self driving, not for you to fiddle with). If Tesla had some idea of ergonomics, the Model 3 would be a truly excellent car to drive, pure fun, but Elon himself chose to wreck it as best he could.
The funny thing is, I remember the first time I was in the USA, in 1993. I rented a car of course, with automatic transmission. Don’t remember what it was, nothing special. But it had this crude and basic, but very efficient cruise control with something called “droop”. It’s the same thing we have in turbine controllers, so I noticed it at once. The way it works is when driving uphill, it will slack a bit when more power is applied, thus the speed will decrease. When running downhill it will add a bit, so the speed increases. For fuel efficiency it is therefore exactly what you want. When there is no undulation, it stays put. In Pullman, Washington it is undulating terrain all right, and I drove miles and miles just checking it out In this older cruise controls, you don’t set the speed in numbers, or by the car itself, you just push “set” at whatever speed you are at.
