ezgo txt 36 volt charger/batt problem

[xltaylor]

Guy brought this cart to me to fix. One year old batteries were low, took almost 2 gallons of distilled water to refill them all. I charged 2 batteries at a time until enough voltage present to activate the charger. I plugged the d.c. side into the cart and got a green light then plugged in the a.c. to the wall. Relay chatter noise then a bang and electrical flash from the charger. Got a steady flashing green light as it should because it was below 80% charge. Opened up the ezgo powerwise qe charger to find a couple legs blown off a transistor at the heat sink. No problems charging with automotive 12 charger, can anyone think of something that would cause this other than the junk charger itself? I don't want to plug another cart charger up blow another one.