Motor randomly stops spinning

[jpearman]

You are tripping the motor PTC, sending power of more than around 25 when the motor is stalled will cause the PTC to trip after some mount of time. Search the forum and you will find lots of discussion about this.

Lots of technical info here.

PTC performance measurements

I’m going to be posting some information over the next couple of weeks with real world measurements of the PTC components in the VEX products. First a refresher, PTC is an acronym for Positive Temperature Coefficient, and is a passive component used to protect electronic circuits from over current conditions. This device is actually a type of thermistor, current through the device causes a small amount of resistive heating. If the current is large enough to generate more heat than the device c…