Hey guys I have a question. I’m getting a very large spark when trying to connect my batteries in series. So much so that it slightly damaged the battery terminal. Is this normal? I’m not connected to anything else, just the two batteries together. Back story: I have two 100ah 12v battle born batteries. I’ve been running a 12v system but want to convert to 24. So I charged them up in earlier in the week using solar. Once they were floating I totally disconnected them from my system and left them sitting in parallel all week just to make sure they were at the same voltage before trying to put them in series. This morning i disconnected them and measured them individually. Each read exactly 13.5 volts. So I started hooking up in series and pop! Huge spark. I’m like wtf? So I thought maybe this was some kind of quick discharge (sort of like when you discharge a capacitor) but sure enough it happened again the second time I tried and was just as strong a pop. The lug got black and the battery terminal got slightly messed up from the arc. I did not try again for fear I may short one of the bms’. I’ve heard of large sparks if your hooking to an inverter but that is not the case here. What do you guys think is going on? Large rush of current from one battery to the other? But why if they have been sitting in parallel for a week? Any help would be appreciated. I’m slightly nervous to try again.