Using motor to prevent rollback

[CarterStC]

Does anyone know if using the motor to keep the car from rolling back downhill, like "riding the clutch", and using the accelerator to push the car forward and let it roll back over and over is bad for the motor vs using the brake?

It is kinda fun and oddly satisfying while I'm waiting for my gate to open...

 

[Kant.Ing]

Shouldn't be bad for the motor, since this method is used to generate heat for the battery pack of Model 3 while parked.

 

[CarterStC]

Shouldn't be bad for the motor, since this method is used to generate heat for the battery pack of Model 3 while parked.

Curious how it is used. I'm referring to driving the car uphill a bit and using motor resistance to slow the roll back, then repeat. I don't believe the car moves while parked. Are you saying they push the motor forward against the brakes to generate heat?

 

[nvx1977]

Curious how it is used. I'm referring to driving the car uphill a bit and using motor resistance to slow the roll back, then repeat. I don't believe the car moves while parked. Are you saying they push the motor forward against the brakes to generate heat?

not the brakes. within the motor itself. effectively turning the motor into a resistance heater.

 

[mongo]

Shouldn't be bad for the motor, since this method is used to generate heat for the battery pack of Model 3 while parked.

not the brakes. within the motor itself. effectively turning the motor into a resistance heater.

I'm pretty sure the heating comes from running the switching devices in the inverter in a resistive mode. The windings on the motor are too low resistance to generate much heat (resistance means power loss and lower efficiency) , and the motor cooling is through the case and oil system (so a lot if heat would be lost to the environment) .

The inverter has a glycol cooled heatsink that the IGBTs or MOSFETs mount directly to.

 

[animorph]

I can't think of why it would be bad for the motor. It just uses energy from the battery unnecessarily, lowering your efficiency. Some people really care about that, others not so much. Up to you I guess.

 

[RDoc]

I can't see how it would hurt anything. I've done it on occasion, although I try to keep the car stationary by just having the motor apply enough torque to prevent the car rolling.

OTOH, normally I just use the brake hold feature.