Regen braking on ice.

MX5huggy

With the first period of sustained frosty weather since taking ownership of an i3 I was thinking how will the car behave when using regen on icy roads?

It’s perfectly possible to drive the car in normal conditions using only the accelerator.

DUTR

Whatever system is on a car, it cannot defy the laws of physics.

forgotmyname

Pump the brakes? Is it the 1970's?

I bet the ABS can pump the brakes way faster than most drivers can.

missile

Can you turn the regen off when conditions are bad?

Goudy

I'd have thought it would be a bonus, it should be a far more progressive way of slowing the car down in slippy conditions than grabby brakes.

With off road driving techniques in slippy conditions it's preferable to use engine braking rather than brakes, just the engine braking is now feed through the electrical generator on an i3.

If you drive to the conditions, like everyone should, I think it would be a boon and you'll not have any problems.

Car_54

martins_fan wrote: »

I think the short answer is yes.

Eh? There wasn't a yes/no question.

bhjm

MX5huggy wrote: »

With the first period of sustained frosty weather since taking ownership of an i3 I was thinking how will the car behave when using regen on icy roads?

It’s perfectly possible to drive the car in normal conditions using only the accelerator.

no difference to a normal car. The Regen happens inside the car and not between the road and the car.

Herzlos

bhjm wrote: »

no difference to a normal car. The Regen happens inside the car and not between the road and the car.

Technically the regen is happening with the engine slowing the car down, rather than the brakes trying to use friction to stop the wheels. So with regen you're not going to lock the wheels up, and it should be a bit more controllable.



As said - if you want to go down a steep hill, you're better off using engine braking so this would be similar.

bhjm

Herzlos wrote: »

Technically the regen is happening with the engine slowing the car down, rather than the brakes trying to use friction to stop the wheels. So with regen you're not going to lock the wheels up, and it should be a bit more controllable.

As said - if you want to go down a steep hill, you're better off using engine braking so this would be similar.

what you describe in your first part is engine or compression braking - regen braking works like a dynamo on a bicycle.

almillar

With the first period of sustained frosty weather since taking ownership of an i3 I was thinking how will the car behave when using regen on icy roads?

It’s perfectly possible to drive the car in normal conditions using only the accelerator.

Quite well, I imagine. Just like an ICE, you need to drive smoothly. You're driving a very responsive, RWD EV. If it were an ICE, you would be advised to avoid using the brakes, and try to use engine braking more, just to smooth things out a bit, and avoid jolts that could cause a loss of traction.

Translate that over to 'one pedal driving' and it just means that you should be even less likely to go near the brake pedal. Regen can be considered engine braking, but in most EVs, stronger. I've driven an i3 and it was great, and the regen can be very strong. So just drive smoothly. Put it into whatever Eco mode dumbs down the accelerator (and regen) response most, making it easiest to drive smoothly. Unlike most BMWs, you do have weight over the rear wheels, so you might do better than most.

Pump the brakes? Is it the 1970's?
I bet the ABS can pump the brakes way faster than most drivers can.

I think we're trying to avoid having to use the ABS.

Can you turn the regen off when conditions are bad?

In a mild form, it just acts like engine braking, no problem. Jumping on and off the throttle at high revs in an ICE would cause problems too.

So with regen you're not going to lock the wheels up, and it should be a bit more controllable.

Less likely, not impossible. And if you have a gammy foot, regen is more than strong enough to lock you up in ice. So is strong engine braking. Especially on a RWD car.

Scrapit

Having not driven the vehicle in question however the Regen cannot possibly work if the wheels are locked because of physics. I would assume then the regen system whilst it may retard speed it shouldn't stop the vehicle completely.