2 12 volt batterys or 2 6 volt
what gives me the most bang for my money. every other rig that I have bought always had 6 volt battery's but the new one has 2 12 volt. not sure what works better.
Forum Discussion
pnichols wrote:
For clarity, draw a diagram of two 6 volt batteries (showing three cells in each battery) in series making of up a 220 amp hour bank. Then draw a diagram of two 12 volt batteries (showing six cells in each battery) in parallel making up a 220 amp hour bank. It will then be clear that each 6 volt battery cell has to generate - day in and day out - twice the current of each 12 volt battery cell.
I'll bet that the plate mass of each cell per amp of current created is about the same for both apples-to-apples battery types ... given equal quality of construction. If that is close to the situation, then I'll further bet that the 6 volt battery plates - since they're creating twice the current for each cell - BETTER be thicker so as to have twice the mass so that their overall erosion life-span equals that of the thinner 12 volt plates that create one-half as much current.
I would suggest that the 6V plates are wider, with 2x the surface area of the 12V plates, thus conducting 2X the current. The thickness/density can be the same.
I find it hard to digest that two high quality 220 amp hours each, 72 pounds each, 6 volt deep cycle batteries will intrinsically outlast two high quality 110 amp hours each, 72 pounds each, 12 volt deep cycle batteries.
One need not jump to a conclusion based on what is commonly stated by others. It merely takes some head-scratch thinking about what most likely has to be going on with chemistry, currents, and materials. I'm not advocating that the situation is ONLY plate mass dependent - just that the situation is MOSTLY plate mass dependent.
I would agree. Unless there's some inherent, large advantage in having fewer, larger cells, the argument should not be between 6V vs 12V batteries. But between plate thickness/density (longevity) versus total plate surface area (high C.A., less V drop under load).
EDIT: or rather as Mex later points out: hard, dense paste plates vs the more porous, soft plates in Marine/RV batteries
It just so happens that most 12V batteries are Marine/RV and so tend to have lower longevity but higher C.A. and less V drop under load. If autos/boats still used 6V starting motors, and 6V starting (or marine/RV) batteries were still available, the issue might be clearer.
