"Backdriving" Motors -- Safe for Victors?

[DonRotolo]

Originally Posted by Ken Streeter

This would backdrive the motor for just a few seconds, surely for no more than a couple thousand rotations.

A couple thousand in a few seconds?

The back EMF produced by a motor is proportional to the motor shaft speed. If you turn the motor at 2 or 3 revs per second, you will see only a small voltage, but at 6000 RPM (100 revs per second) you'll see quite a good amount of power.

The Victors can handle reasonable energy from backdriving, as dtengineering stated, but don't go wild and expect it to last.

It is more likely your Victor failures are due to other factors, such as metal shavings in the Victors.

Teams should make it a practice to protect their Victors (all the electronics, really) from the mechanical folks, with their saws and files and stone axes...

Team 1676 uses a blanket to cover everything when there's work being done.

Don

[Mike Betts]

Ken,

We have repeatedly performed both of your scenarios over the years and have never damaged a Victor in this way. We have only blown one Victor about 6 years ago and that was attributed to an aluminum chip which fell into the heat sink assembly.

I would not worry about it...

JMHO.

Mike

[JamesByrne]

Same here, never damaged a victor. We backdrive our robot without thinking to get it moved in the build area.

I do not think it will hurt them.

[Al Skierkiewicz]

No need to worry here, the diode protection in the FETs provide a current path when the power is removed that routes the current to the input terminals of the Victor. This current will light up the LEDs on the Victors and will move the fans.
Although pushing the robot with the power off will not damage the Victors, you might be putting undue forces on the mechanical systems and wheels.