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ron_dittmer's avatar
ron_dittmer
Explorer III
Oct 13, 2014

Batteries: Two-6V In Series, or Two-12V In Parallel ???

Before spring I will be replacing our two 12V Walmart coach batteries. Our 7 year old rig has it's original Tripplite 2000 watt inverter/charger similar to THIS ONE. I was thinking of replacing the ...
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DiploStrat's avatar
DiploStrat
Explorer
Oct 14, 2014
map40 wrote:
2 12 volt batteries in parallel will pray from each other giving you a parasitic power loss proportional to the consumption. To be able to make it work efficiently you will need battery isolators.
2 6V don't have this problem. ...


Actually, that is not quite correct. ANY two or more batteries (or cells) connected together, whether in series or parallel, will seek to reach a common voltage. Hence the counsel to always use batteries of the same type, age, capacity, etc. together in the same bank.

12v batteries connected in parallel do not need to be isolated from each other and if you used a diode isolator, that may have caused your problem. Diode isolators cause a 0.5 - 1.0v drop, depending on the amperage flow. See: Diodes

Connecting two to four batteries in parallel, be sure to wire them diagonally. That is take the positive feed from one battery connect the negative return to the battery furthest from it. If you connect positive and negative to the same battery it will end up doing most of the work. More than four batteries? Run a separate positive and negative to each battery. See: Wiring a Battery Bank

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