As I mentioned before, I have a battery bank at a remote house and one in my truck. I been charging the one in my truck while driving or at the main house using the grid.
Ok, about a week ago, (the day I drove to Grizzly and got my lathe/mill combo) I charged the truck bank for about 300 miles, or about 6 hours (plus extra). This was about 3 hours, a few minutes here and there, then 3 hours again, spread out over about 10-12 hours. Not just all at once.
The truck bank is 4 large trojans, about 345 amphrs each, 6 volt. These are wired 2 for 12volt, and both sets of 2 are connected for 12v also. Before starting my long trip I had ran these all a little low charging the bank at the remote house.
My charging methode was simple, jumper cables connected to the first set and the other end to the truck battery. Now all the way there I was watching the amp gauge in the truck, nice good charge being sent. Driving around up there was good charging, and driving home was decent charging though I was running the heater and headlights, plus the batteries should have been getting pretty well charged by then anyway.
No problems then. The next day though I had a dead battery and the truck would not start. Hmm, that was strange, nothing was left on, I still had the cables for the trojans connected also. I should have had about 700amphours reserve on the trojans.
Well I jumped off the truck, it started, amp gauge showed charging well, and after it ran for awhile I shut it off and it would start up again fine. About 4 hours latter it was dead again. Hmmm.., So I disconnect the cables from the trojans, jump the truck, connect a 40amp smart charger to the trojans. In a few minutes running the truck has plenty of juice to start on it's own and no more problem. The trojans I let charge about 24hours and they showed taking a 2amp charge when I disconnected them (the charger showed 41amps when I started). I have 2 other trojans in the truck (seperate) and I charge those with the smart charger till it shuts off as full.
Now yester day after all this charging I go to the remote house and connect to the inverter. Dead Trojans, the set of 4! What the heck, my inverter doesn't even see them being there. Ok I connect the other set of 2 and all is well, I have power till late today.
So now I get home and dig out the 50amp load tester and start testing. Nothing has been connected to the set of 4 for over 24 hours now. I first notice hissing (before I do anything), I pop caps looking at water levels and I got batteries bubbling like crazy, water is fine. So I pull the wires connecting them and test. Each set has one battery full charged and holds strong with a 50 amp load tester. Each set has a 4V battery and of course that does not hold any load. These are also opposite ends of the sets. In other words it the first battery in the set on the left, the second battery in the set on the right. So what I actually have is 2 sets of 10volts each??
What could have caused something wierd like this? These are recycled trojans from a scarp yard, not new ones. But I have been getting great service from them, and now this. The battery in my truck is fine and it would have been the first to get currant from the altenator so I don't think it was that I burned them out overcharging. Also they all got the same amount of bouncing or what ever on the 300 mile drive.
Any ideas?
I will rewire the sets and do some more testing and probably pulse charge the 4v ones again and such, but I found this to be rather strange.