Government Regulations regarding Regenerative Braking

Government Regulations regarding Regenerative Braking

I' am an automotive student interested in electric vehicle technology. Recently I was just trying to understand the difference between regeneration strategy in BMWi3, Tesla and Prius. It seems to be something with blending through brake pedal or through throttle lift off. Also, these differences also gave rise to different government regulations like Category A and Category B, so I just wanted to know what category do the above cars fall in.

vperl | 30. elokuu 2016

With perpetual motion, and new strategies on climate change

UnshodBob | 30. elokuu 2016

@ms.gitlakshya - @vperl is acting up a bit lately. Ignore that post. I apologize for @vperl.

I don't know where the Tesla falls within the regulations you are interested in. Sorry. The Tesla is easily controlled with careful pressure on just the accelerator pedal. Brakes are only really needed for the final few mph to zero, except in any emergency situation, of course. Regen braking falls off sharply near 0 mph due to the motor design, I'm told. I have no experience with the other cars. Good luck to you!

jordanrichard | 30. elokuu 2016

What government regulations/categories are you talking about? There are no regulations governing how fast a car slows down, only that the brake lights come on to give warning to those behind you that you are slowing quickly.

DTsea | 30. elokuu 2016

There is no throttle on an EV either.

vperl | 30. elokuu 2016

I vote for the perpetual Regen, and climate differential

stevenmaifert | 30. elokuu 2016

If you Google it, you find that some countries have adopted regulations regarding regenerative braking. From what I could find, those regulations were adopted where the government considered regenerative braking to be part of the overall automotive braking system of the car as opposed to being just a kinetic energy recovery system that slowed the car but was ancillary to the requirement to have brakes. I don't know the answer to the OPs question, but I have observed that, unlike my MS, when I apply the brakes on my wife's Leaf, the regenerative braking increases proportionally to the pressure applied to he brake peddle in addition to the friction braking;

EVRider | 30. elokuu 2016

This thread might help you understand implementation differences between regen braking in the Tesla and i3: If you search the forum for "regen braking" you'll find more like this. (See if need help on searching.)

Can't help you on the regulation or strategy questions.

dansplans | 30. elokuu 2016

lol @ DTsea | August 30, 2016
There is no throttle on an EV either.

throttle = accelerator

ms.gitlakshya | 31. elokuu 2016

Thanks guys, I will keep looking, and maybe share the information if I get any :)

fgaliegue | 31. elokuu 2016

I guess what you want here is investigate on two fronts: the technology and the regulations.

Also, you say that you are a student in automotive technology (I guess); do I take it that what you want to do is match implementations against regulations?

In this case, well, you may already know that regulations are always late in the game; only when a (set of) technology(ies) starts to be in sufficiently widespread use do governments actually seek to categorize them. One example is the autonomous driving levels as defined by the NHTSA in the US which only came years after the first technologies enabling autonomous driving appeared, and even now, the classification made by NHTSA is criticized on various fronts.

Shall I say, good luck with that? :)

DTsea | 31. elokuu 2016

Dansplans do you call volume knob a throttle?

I am an engineer so use of throttle for a machine with no air intake bugs me! :)

joer293 | 31. elokuu 2016

AT&T throttle's data plans, but they are full of hot air. :)

Yes, regulations that would cover regen do exist in different places. The regulations were mainly designed for "Heavy Machinery" from what I've read. Think super large Mining trucks, which use diesel-electric turbine power, and huge electric heaters to slow down electrically. Other very large construction machines may fall under those regulations. I have not seen any regulators give any notice to what a light passenger vehicle does for regen braking.

vperl | 31. elokuu 2016

Yep, perpetual, climate differential, on decent, chose option one.

dansplans | 01. syyskuu 2016


Common usage does not mean factually correct, of course. I don't think I have ever used the term throttle, but I am used to the American terminology for most things. My guess it is more common in the UK?

Saying gas is not quite exact either. But we don't correctly say petrol on this side of the pond.

If we tried, I'm sure we could find hundreds of misnomers in common use.

DTsea | 01. syyskuu 2016


The right word ia probably 'accelerator'

Frank99 | 01. syyskuu 2016

DTsea -
Do you also have a problem with having a valve in your guitar amplifier?

And "throttle" is actually a good description of how a PWM motor control works. I haven't looked into the Tesla design enough to know that it's appropriate there, but it's not as wrong as you like to think.


DTsea | 01. syyskuu 2016

A valve is a fluid flow control device, so unless you are talking about a Roman water organ, i cant see why you would put valves in an electronics box.

DTsea | 01. syyskuu 2016

Frank, engineers dont get into etymology. We like to have each word mean one thing. A throttle controls air flow into an engine, not phase synchronization in an AC motor.

fgaliegue | 01. syyskuu 2016

@DTsea at some point you have to "give in", right? Your definition is technically accurate but then the regular joe out there will instinctively understand that "the throttle", when it comes to cars, means "yeah, you know, that pedal under your right foot".

Also, well, it's been some time now that engines have come out where there is no mechanical link at all between the "throttle pedal" and the actual throttling system.

I know your definition to be the most accurate. But dammit, I still refer to "that right pedal" as "the throttle" from time to time... Note that this is really a problem with the English language here; in France we refer to this pedal as "la pédale d'accélérateur" or, for short, "l'accélérateur": a way to modulate your car's acceleration.

UnshodBob | 01. syyskuu 2016

Valve is the UK word for electronic tubes. From

7. Electronics (chiefly British) . vacuum tube (def 1).

I believe Frank99 was using this definition in his guitar amp remark.

vperl | 02. syyskuu 2016

Go pedal

Go flower

Gee whiz, who cares ?

Whoops, forgot, you guys still post on perpetual motion, solar on Tesla car roofs, and other such ideas.. So, an exercise on naming this device is so very important to you guys.

Let's all get back to the dozens of designs of battery types that are so much better and reliable than Tesla. When you guys going to discuss the use of windmills on the roof of Tesla vehicles to maintain a charge?

Thanks for you insightful thoughts and expertise, move on nothing to see here.

Be Happy | 02. syyskuu 2016

@vper +1

You forgot about perpetual charging by running a wire from the cig lighter to the charger port. No need to ever go to a charger again!

Brian H | 03. syyskuu 2016

Do you throttle the petal to the medal?

kevin | 03. syyskuu 2016

I think the Prius is a Category B Phased system, which means that the electric regen is part of the brake system so that when you press the brakes there is regeneration at increasing levels and as you press harder friction brakes are applied. The actual legislation is quite complex, so I can't be certain that the Prius meets all the detailed regulatory requirements for a Category B Phased system, but it is at least Category B.

At one time, as I understand it, the Tesla was a Category A system, meaning that regen was not part of the braking system--it happened when you let off the accelerator pedal, and the pedal brakes were solely friction brakes. I have read some comments that newer braking hardware makes it a Category B phased system. This would be easy to test by setting regen to its low setting and then seeing if energy is recovered when pressing the brake beyond what happens when coasting. I can't try it because my car hasn't arrived.