how to connect two car batteries and still have 12 volts--- also 24 volts?

Answer 1

For 12v, connect the like posts together (++, --) this will give you 12v at the sum of amps of both batts.
For 24v, connect opposite poles(+-,+-)This will give you 24v at 1/2 sum of both batts. amps

Answer 2

Many people know that connecting multiple batteries together increases the amount of power available, but are unsure of how to connect them up. RVers use a combination of 6 or 12-volt batteries which leads to some confusion. Should the batteries be connected in series or parallel?

12-Volt Parallel

If you are using two 12-volt batteries, which a majority of recreational campers use, there are a few things to know before connecting them together.

First, the batteries should be of the same group type; be it group 24 or group 27. Second, they should be of the same age. A new battery connected to an older battery will soon be drawn down to the level of the older battery and therefore won’t last as long.

Connecting two 12-volt batteries in parallel is not complicated at all.

Take the positive post from Battery “A” to the positive post of Battery “B”. Next connect the negative post from Battery “A” and connect it to the negative post of Battery “B”


The negative post from battery “A” and the positive post from battery “A” are connected to the existing wiring connections in the RV.

6-Volt Battery Connections

Many campers, whose electrical needs may be greater than the capacity of a 12-volt battery, use 6-volt golf cart batteries instead. To maintain the 12 volts that is needed by the water pump, inverter, and other devices in the RV, the batteries must be connected in series.

Connecting two 6-volt batteries in series is also simple.

Take the positive post from Battery “A” to the negative post of Battery “B” .





The negative post from battery “A” and the positive post from battery “B” are connected to the existing wiring connections in the RV.

Series - Parallel Batteries

So far this still gives a comparable amp hour rating so to increase that more batteries need to be connected together. Creating a “series parallel” circuit does this. The 6-volt batteries are connected in series to create a 12-volt source, and these 12-volt sources are connected together in parallel
24 volts hook batteries in series postive to negative than remaining negative and postive to load. Hope it helps





--------------------------------------------------------------------------------

Answer 3

Connect positive of one to positive of the other, and negative of first to negative of second - you will now have 12 volts at twice the amperage (used a lot on RV's)
24 volts - Connect the ground of the car to the ground of battery 1, connect positive of battery 1 to negative of battery 2, connect positive of battery 2 to whatever needs 24 volts and ground the item to the ground of the car (unless you are also running a 12 volt system - in this case keep the 24 volt system closed - negative of battery 1 to negative of 24 volt motor and positive of battery 2 to positive of 24 volt motor)

Answer 4

Go to NAPA tell them tou need a series paralel switch then wire it according to diagram in Motor Repair manual available at the library.This lets you have both 12v and 24v just as old semis had in the 50s and 60s they used 24v to start then ran lites etc on 12v.

Answer 5

Wire them in series for 24v, put a jumper at the center for 12v.

Positive terminal
24v + -----0____
| |
| |
| |
- -|---0|____|
12v+ -|---0____
| |
| |
| |
- -----0|____|
Ground