Yea, too much or too little voltage will cause these things to twitch.. I've not experienced the high voltage twitch, but when my rx batts get low the steering will twitch and lock up, if I first give it full throttle and hold it there.. (This is a nitro vehicle, controlling 2 servos) I've been using regular duracell 1.5v AA's in mine.. Was gonna go with some rechargeables, but the lith ones I've seen are only 1.2v and I dont think I have room for 5 of those in my stock battery box..