I have an almost new 19t Fantom motor. It has been run for 4 5 minutes races and maybe 10 minutes of practice. Anyway, during practice I thought my battery had died on me, the car gradually got slower and eventually can to a complete stop (but is had full steering I didn't notice at the time). It was a new battery, so I thought it just dumped on me. I went home and discharged the battery and found it was almost half full. I thought it was odd, but went ahead and charged it again. I went out to run my car with it and it didn't move. I had steering, but no "gas". It would kind of run if I pushed the car while the throttle was on. I seemed to have full power only when I was rolling the car backwards
It would completely die when I let go. So I took the motor apart, it all looked OK and reassembled it. The motor worked excellent for about half the battery then it died. I have no idea what might be causing this. Both the battery and motor were not even hot to the touch. Any ideas? This has happened three striaght times. And it happens with different batteries.