Originally Posted by ClintThrust
It's 4 years old. Follow up question; it is a 6 cylinder cummins diesel, would it need 24 volts to start or could I just buy 1 battery?
The starter is 12 volt. The two 12v batteries are connected in parallel to double the available cranking amps.
You may get away with one battery in warm weather but you are likely to have trouble in cold weather and reduce the lifespan of the battery.
My 6 cylinder Cummins all have two or three group 31 batteries in parallel.
I just replaced a set at BatteriesPlus. I paid a bit over $125 each including tax and environmental fee. If you have a Rural King near you I would check them out. I have heard of them putting Group 31's on sale for well under $100each.