Quote:
Originally Posted by cochise
With 2 6 volt batteries you will get better amp/hrs than with 2 12 volt.
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This is not true. Amp hours (Ah) is a measure of capacity, which in flooded lead acid batteries, is generally directly proportional to the amount of lead in the battery. The only way to get significantly more capacity is to add more lead. Goto Trojan's website and compare Ah ratings with weight.
All else being equal, two 12v batteries rated at 100 Ah each will provide just as much energy as two 6v batteries rated at 200 Ah each.
Quote:
Originally Posted by cochise
The 2 12 V will try to equal each other out.
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This can indeed be an issue, and I think is the real advantage to using two 6v's over two 12v's. Charging can also be an issue -- one of the batteries will end up being charged with a different amount of energy than the other, so either one will be overcharged or one will be undercharged. Look at how most batteries are constructed -- 12v batteries typically have six 2v cells, and 6v batteries have three 2v cells.
But you can resolve this issue by not wiring the batteries in parallel and using a battery switch to switch each battery in and out of the circuit.
Quote:
Originally Posted by cochise
Besides the 6 V golf cart batteries are build for more amp/hrs.
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There isn't true as a generalization. 6v golf cart batteries are "true deep cycle", which means they can be discharged to a lower rate than cranking batteries before damage. So in a sense, yes, you can get more Ah out of them over the life of the battery if you deep discharge the battery, because if you deep discharge a cranking battery very often, as if often the case in an RV application, you will soon have to replace it. But if you don't deep discharge them, I don't really see an advantage to using a deep-cycle battery. But there are also "true deep cycle" 12v batteries, such as those made for trolling motors. They work just as well as the golf cart batteries.
There are some advantages to using two 12v batteries, however. For example, if one of your batteries ever dies, you still have a 12v source of power. But that is probably an unlikely scenario.
Dave