Motor rotating while throttle not engaged = burned motor?

[Jason Toberman]

Hi!

Quick question. We tried having a car that had reverse this year, so unlike our previous car that had a clutch, our sprocket was bolted to the live axle - though this time we let the "magic smoke" out of our motor. Basically - we wanted to coast (with no smoke) while having a live axle with a fixed sprocket. We were operating a dc brushed motor and we think the culprit was that when we were "coasting" (throttle not engaged) the motor was still spinning while connected to a cheap ebike controller (the cheap $20 ones on ebay - no reverse). Our speed controller is fine, but our motor ended up smoking. 

We think that having the motor connected caused it to be in a "electronic braking" mode or somehow else made it not very happy for moving when the throttle was not engaged. Has anyone had this case before? We are thinking to have a relay system that disconnects the motor from the speed controller when the throttle is not engaged.

We are also trying to use a 48V DC brushless motor (A Boma motor found on ebay). It has three phases and its speed controller can go in reverse (though it is also a cheap ebike controller). Do three phase brushless motors run the same risk as brushed motors when rotating without the throttle engaged?

Thanks

Jason