I might have screwed up(12v Charger, 6V Batts)

[_LifeInTheWild_]

I got the wonderful idea that I would run two 210ah golf cart batteries in a series for 12v. It seems that my charger might not be compatible with that. I have a ProMariner charger and according to the documentation it says to connect each set of leads to a single 12v battery. Would I be a fool for connecting my bank to a single set of leads? Has anyone done this? If it turns out to be a questionable idea, what chargers do those with 6v batteries use? Thanks.

[WoodenKetch]

I connected one of those chargers to 6v batteries in series, worse than you I have four of them in a series/parallel combo making a 12V bank. Obviously you need to connect the charger across the batteries so there is 12v between the connections. It works. Charger life could be reduced , and the math for the special equalization or desulfate cycles are probably a bit wrong. But voltage is voltage and amps is amps. The real issue is the charger is undersized for the capacity of the batteries. I think you'll be fine, my batteries are charging right now without issue.

[markcouz]

Two 6v batteries in series is a single 12v battery - no problem.

[_LifeInTheWild_]

Originally Posted by WoodenKetch

I connected one of those chargers to 6v batteries in series. Obviously you need to connect the charger across the batteries so there is 12v between the connections. It works. Charger life could be reduced , and the math for the special equalization or desulfate cycles are probably a bit wrong. But voltage is voltage and amps is amps. The real issue is the charger is undersized for the capacity of the batteries. I think you'll be fine, my batteries are charging right now without issue.

My thinking is that I am a weekender and not a cruiser yet. The "rule of thumb" for chargers is 10% of capacity. I figured I am close with the 20a charger. I would like to bump that up, but that is a lower priority for this summer. I grabbed a couple of cheap golf carts to get me going and am using the charger that was on the boat when I bought it. Since buying the boat, I have started to educate myself on marine electrical systems. I learned that I bought a fire bomb. I decided to redo the electrical this year. I most definitely under estimated the cost to do it properly. a new charger and solar is all that I have left to buy, but that will wait.

[Fore and Aft]

Lifeinthewild I am glad someone reads those instruction manuals. I don't bother until something goes wrong and then I wonder why I never read the manual.
Cheers

[Cadence]

Originally Posted by _LifeInTheWild_

I got the wonderful idea that I would run two 210ah golf cart batteries in a series for 12v. It seems that my charger might not be compatible with that. I have a ProMariner charger and according to the documentation it says to connect each set of leads to a single 12v battery. Would I be a fool for connecting my bank to a single set of leads? Has anyone done this? If it turns out to be a questionable idea, what chargers do those with 6v batteries use? Thanks.

You're OK. You created a 12V putting them in series.

[Dsanduril]

Any lead-acid battery is actually a series connection of smaller 2V “batteries”. We call them “cells”, but each cell is a distinct battery. A 6V battery is 3 cells in series, a 12V battery is 6 cells in series. Whether the cells are in 6 cases (6 x 2V batteries), 2 cases (2 x 6V in series), or one case (12V) really makes no difference. There are certainly things to pay attention to when joining batteries or cells, but as long as they are all alike the charger will never know the difference.

[roverhi]

You are ok as long as you connected the negative side of the charger to the negative terminal of the battery that is the ground side of the series wired batteries set up and the positive side of the charger to the other battery's 12v positive terminal. Don't connect the charger to the terminals of each individual battery as then you will screw up the batteries by charging the 6v battery with the 12v charger.