What is KERS or regerative braking on an electric car?

[Stuart Wright]

One of the clever ways that electric cars conserve electricity (to extend their range) is by recovering it when braking or slowing down. Exactly how they do this doesn't really matter so long as it works.

It's called by various names by different manufacturers and organisations. Some refer to it as regenerative braking. Some (including the Formula One community) call it KERS or Kinetic Energy Recovery System.
Let's face it KERS is easier to say than regenerative braking.

When braking in a car, the forward energy is lost in heat in the brakes as you apply them.
In electric cars, brakes are often (usually) not used, but instead, a mechanical system is used to convert that energy into electricity which is put back into the battery.

This method of re-charging the battery has been named by some disingenuous manufacturers as 'self charging' when referring to hybrid vehicles. It's misleading as it implies that the car charges itself without having to put any fossil fuel into it first. Which, of course, it can't.

It's important to remember that you never put as much energy back into the battery by braking as you took out of it when accelerating in the first place.
But KERS is an important component of the technology which helps extend the range of an electric car.

 

[Jake]

Up until last weekend I had always used level 3 regen but as an experiment to gain more miles/kW it was suggested lower levels of regen could be more beneficial. After travelling 60+ miles with regen 1 I found I used the brake more times in that journey than I had done in the previous 19 years of 'electric' motoring. Over those 19 years I became accustomed to using the accelerator as a regulator to adjust speed up or down as required very rarely touching the brake only to end or start the journey. I will try level 2 over the next day or two but don't really see what difference it can make. If you need to slow down then surely feathering the throttle on regen 3 is better than having to use the brake on regen 1?

 

[Chrispydoc]

I tried moving from my usual level 3 last weekend. I didn't like it on either 1 or 2. I think any extra possible energy savings would be minimal. But without proper tests...I can't be sure.

I'm going back to level 3......my brake-pads will certainly benefit!

 

[Deleted member 823]

I use level 3 the most, 2 feels like the drag you'd get with an ICE vehicle off the power, 1 feels like a two stroke motor - hardly any (engine) breaking!

When I was a kid, on my bicycle I had a dynamo that powered the lights when the wheels were moving. Why can't something similar be built into electric cars, in that when the wheel is turning it generates power all the time?

 

[Jake]

I'm with Chris and going back to using level 3 regen as standard. Reading the hand book suggests levels 1 and 2 are for use in icy or poor adhesion surfaces so as not to lock the driving wheels.

 

[MEH]

The excess energy energy used to power the wheels will be greater than the energy produced unless somebody creates perpetual motion and then you would need a AA battery to power the entire car

You don't get owt for nowt

 

[Deleted member 823]

The excess energy energy used to power the wheels will be greater than the energy produced unless somebody creates perpetual motion and then you would need a AA battery to power the entire car

You don't get owt for nowt

I get that, but putting some energy in rather than none can only be helpful (which is what regen does).