1515 1.5y very hot

[mohanjude]

I think the advice that you should NEVER run the motor without load is sensible. However in real life things dont always happen as they should. Manufactuers and everybody else will blame running a motor without load as its cause for failure. Now if life was that simple then we can assume that no motor should ever fail under load. Of course not - motors will fail for any reason. I challenge anybody to say that if you apply 7.2 V to a 1Y motor it will spin beyond its capability to cause self destruction. It is not going to spin at 50, 000rpm simply because there is no load.

So what is a load? A pinion mounted to the shaft?

However if you apply 25V without load then it is a different matter to this motor as clearly it has potential to over rev. The number of times I have been racing flat out when suddenly the pinion comes flying off - ie motor is not under load at full throttle - I should have dozens of burnt motors / busted magnets etc..

Unless someone can do a detailed analysis and also do a detailed forensic type investigation into the setup that led to the motors destruction I think this type of failure is going to a guess on what went wrong.