Quote:
Originally Posted by davidthefat
So having a closed loop system that constantly compensates is a bad thing for the motors?
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Not necessarily. Certainly it's done frequently in FIRST without harm. Whether it works depends on the average load applied and the terms of the the PID loop. I couldn't possibly hazard a guess as to whether your use is kosher without seeing it.
The simple test is: does it work? The motors PTC circuit will open before the motor is damaged, so that's the budget your are working within. Over the course of two minutes does the motor heat to the point of the PTC opening up? If so, adjust the loop to reduce over controlling of the motor or reduce the load. When you can make it through the match with everything still working then you're fine.
The nature of the PTC is that it acts like a breaker more then a temperature sensor. A hot motor 'preloads' the PTC, but it's really intended to protect the motor from stall current, not over use (they can only run for a few seconds before stalling in a car, after all). It's pretty rare to just plain overheat the motor.
If you're really pushing it on match turnaround, and starting matches with hot motors, you can always spray them down with coolant. It won't do the motors lifespan any great favors, but how long do they really need to work for anyways?