Yes, some guys "zap" them. This seems to be pretty common in 17.5 blinky class where everyone is on a pretty level playing field (or are supposed to be) and are looking for that little edge. Funny thing is I've heard a million times that someone actually improves on lap time as the race goes on because power is a little too much at the start. I never charge above the recommended rate, I've got extra batteries so I'm never in a hurry for a fresh one. And yes, it will definitely shorten the life of your battery