Let me preface this by saying I am an electrical idiot and hooking up my boat batteries is about as advanced as I get....

So I went to pick up my boat from storage today. It has been sitting since December with fully charged batteries before I put it up for the year. Not sure if that matters, but now ya know.

I needed to disconnect my batteries to clean my bilge area and install my new charger. When I went to disconnect my first trolling motor battery the negative terminal wires came off fine. This battery had the jumper cable connected to the negative post for the series of my two trolling motor batteries. When I went to disconnect the positive terminal .... POOF. Big spark. Like a nice firework inside my bilge area. About 1 foot by 1 foot. I am wanting to know if any of you can see why this happened. I dont want it to happen again as underwear is expensive.

A couple other things that I am not sure matters or not. I was using a socket wrench. I loosely put the the nut back on the negative terminal before I started removing the positive one.

Also want to know if this could have damaged the battery?

Thanks

Sounds like the back of the socket wrench touched something else that was metal! As long as the battery seems to still work, and you do not see any protrusions from it, you should be fine!

Jeff

Something made contact across the terminals of the battery, or wires connected to those terminals made contact somehow. Do you have a tin or glass boat?

Glass. My lids are aluminum though. Would me laying on the aluminum lid matter?

I went back out an disconnected the battery with no problem. Admittedly very freaked out.

Either the cable you took off first got over on one of the others or you shorted your wrench across the battery some how. You should be able to look at the batteries/cables and see the big arc marks it should have made

If it were the wrench that made the connection it may have a chunk burned out of it like one of mine does.