How do you wire dual batteries in series?

I've got a few KC's and just installed electric fans on my 72 CJ5. I'm going to put in dual batteries. I read some of the forums in here on wiring in series so you keep 12 volts. How do you do that?

 

Actually, I believe that running 2 12 volt batteries in series will produce 24 volts. Parallel is what you want. Think jump starting a car.....
http://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/DC-Current/SeriesParCompare.html

 

Series doubles voltage, parallel doubles current.

 

Wire the black leads in line on the negative posts. Do the same on the positive posts with your red cables. Remember, parallel wiring doubles current capacity(amps), series wiring doubles voltage.

 

The easiest way to think of it is as if you are enlarging the battery, which you are. You run wires (jumpers between the batteries using the same size or larger wire that is in there now) positive to positive and negative to negative. Then when you tap the batteries to the vehicle, the wires can come from one or the other battery.

I run an International 4700 truck that has dual batteries in it now. When I got it, it had one of those BIG batteries in it, an 8D I think. With the two batteries, I didn't lose any capacity to do electrical work but I cut the physical size of the battery in half, making it more manageable for me to remove and install. The first post is correct in that if you connect pos of batt 2 to neg of batt 1 and pull your vehicle off of pos of batt 1 and neg of batt 2, you will get 24 volts. Think of that as like a flashlight with more than one cell in it. If you remove the batteries from the flashlight, you will notice that the voltage of one battery is 1.5 volts. What they do in the flashlight is "stack" the batteries pos to neg and the bulb pulls from the ends of the stack. In a two cell flashlight, that voltage would be 3.0 volts.

Clear as mud???

HTH

 

So positive to positive, and negative to negative. Got it.Thanx guys, I appreciate it.

 

A new battery and a weak battery will also make two weak batteries.

Consider a battery isolator, both charge but you can jump the dead one from the other.