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 !!!