Small spark from battery charger

:confused: I was recently putting some inline fuse holders in my leads on my onboard chargers, had the tube type, but replaced with blade type, and whan I was hooking the leads back up I noticed an small spark on the lead when I attached it to the battery. Just curious what might have caused this ?? Is there something in the charger that would have caused the spark ?? Have a Guest "Charge Pro" 2 bank charger attached to two batts. which power my trolling motor and have one 12 cir. off one of the two batt. going to front of boat to power fish finder and a outlet for a spot light. The third batt in boat is start batt. and it powers dash lights, running lights and starts motor. Its has a seperate onboard charger, single bank, just for it. I double checked and there was nothing turned on or powered up when I attached this wire. Anyone have any ideas on what might have caused the spark ? Thanks in advance !!!

So you disconnected the leads at the batt, then changed out the in line fuse holders, and hooked/connected the leads back up to the batt, that's when a spark happened. If you hooked the + up 1st, then the -, you probably got a spark when the - touched as the electrical circuit was complete when the - was hooked up, and is normal. you did hook + up to + and - to - didn't you?

If you didn't have the charger plugged in, and nothing turned on, then you have to investigate further. IMHO there should have been no spark. I had a bad pump that caused mine, one of the things I found while working thru the punch list after buying the boat.

It may have just been a capacitor discharging. Check it again. If it was a cap it will just spark once until you plug the charger in again.

Hey thanks guys for all your help, after reading through all, I think its probably a capacitor in the charger. It will only spark once when the lead is connected. Thanks again for all ya`lls input !! Thumbs Up