How to Wire Two 6-Volt Batteries In Series to Double Output Voltage

Updated 07/31/2025 | Published 08/07/2013

Question:

I need a wiring diagram for wiring 2-6v batteries to produce 12v

asked by: K M

Expert Reply:

To wire two 6-volt batteries in series to produce 12-volts, you would connect the load to the positive terminal of battery # 1. Connect the negative terminal of battery # 1 to the positive terminal of battery # 2. Ground the negative terminal of battery # 2.

I have produced a diagram showing the connections for you.

expert reply by: Mike L

click to enlarge

Cam P.

6/15/2020

How can I add an Isolator to 2 6V Batteries that are wired in Series. I need to be able to charge them while driving. Thanks

Chris R.

6/19/2020

I linked an answer page below that does a really nice job of explaining how this is done.

Helpful Links

question-336938.html

Benwaldie

6/29/2020

Thanks Mike L the wire diagram made it super easy and I was on my way.

Alfred

8/25/2024

Can you wire two 6 volt batteries in series Parallel??

Mike L.

10/11/2024

@Alfred You can run them in parallel or in series (both are wired differently and provide a different voltage output). If they're wired in series, the negative and positive of both batteries are connected together. The remaining positive post would attach to the load and the remaining negative post would be grounded. This would result in a 12V output. If it's wired in parallel, both batteries positive and negative posts are wired together. The positives are connected to the load, the negatives are attached to ground. The output would be 6 volts. I'll link you to a Q&A page that features diagrams showing the connections.

Helpful Links

question-372187.html

William

7/23/2025

I've got a hot water tank but it called for a 12 volt battery on a camper. If I follow the instructions on wiring 2 6 volt batteries to produce 12 vols. You start out with hooking the load side from battery one to deposit connection on camper. The one that ends up on battery too ground side, would that hook to the negative side on the camper. Maybe a dumb question

Mike L.

7/31/2025

@William In order to get 12V output, you'll need to wire the two batteries in series. On battery 1, run the positive cable to the load. Connects that battery's negative terminal to the positive terminal on battery 2. Ground battery 2's negative terminal to the chassis. I hope that helps!