Battery life question

[overtaker]

Which fully charged batteries would last the longest? 1. Two 12v. batteries hooked in parallel running something at 20amps. or 2. Two 12v. batteries hooked in series ( making it 24v. ) running something at 10amps? Assuming all batteries are equal. Thanks.

[Super Fuel FX]

I would gander that the batteries pulling less amperage would last longer. When you leave a dome light on, it takes quite a while to drain the battery. When you leave your lights on (they draw more amps) the battery dies a lot faster.

[overtaker]

True but the watt usage is exactly the same in my scenario.

[ridelong]

The batterys would discharge exactly the same.

The current being drawn in each situation is 10 amps per battery.

[Super Fuel FX]

True, but the amperage is different, per the 2 scenarios given to us by overtaker - one runs 10 amps, the other runs 20 amps. Does this not make a difference?

[H2OPWR]

Both are the same. That said I just went to the local battery outlet last week with the same question. I wanted to run tests with higher amp output than my DC power supply will allow. I came away with 2 6 volt golf cart batteries. Hooked in series the 6 volt batteries have way more amp hours than you can acheive with any set up using 12 volt batteries. With the same size casings the 6 volt batteries have 3 cells storing energy instead of the 6 cells in a 12 volt battery. More lead in a barrery is more stored energy. Also if you are fully discharging the battery then recharging it the golf cart batteries have a far longer life.