It could be the battery, sometimes the lead leads can crack and cause intermetant pulses or shorts... I hope that wasn't the problem.... Let's see what happens at 4500 rpm
Oh, and the acid is pretty weak... it only hurts on open cuts... and then it normally just stings a little. Don't want to get it on your clothes though... it will burn holes in them.. not right away, but a few washes and you will be cursing yourself.