Originally Posted by dennis45
I have seen 120AH 6V flooded batteries in the range of $120 each (or less). So, two (giving you 240 AH) would cost you about 240 plus bucks.
Sorry, the math doesn't work that way. Batteries in series increase voltage, but not current capacity. Batteries in parallel increase current capacity, but not voltage.
Two 120AH 6V batteries in series give you a 120AH 12V battery.
If you think in terms of power, the math becomes a little clearer: power (Watts) is voltage (Volts) multiplied by current (Amps). Or going the other way, power divided by voltage gives current.
- A 120AH 6V battery has 720 WH (Watt-Hours) of capacity. Two would give you 1440 WH. Divide that by 12 volts: that's 120 AH. By going in series, the voltage increased, but the current capacity didn't.
- A 60AH 12V battery has 720 WH of capacity. Two would give you 1400 WH. Divide that by 12 volts: that's 120 AH. By going in parallel, the voltage stayed the same, and the current capacity increased.