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Key Takeaways

  • Wiring RV batteries in series or parallel is a matter of connecting terminals and wires
  • Connecting batteries creates a battery bank
  • The advantage to a parallel connection is more significant capacity
  • The advance to a series connection is more voltage, if you need it
  • The most important tools are instructions and wires that complete the connections.

Wiring RV batteries is a bit different from wiring most vehicle batteries. Let’s talk about how to wire RV batteries safely.

RV batteries are typically wired in a battery bank - meaning with a pair of 12V batteries. You’ll typically want to create a parallel connection which means connecting the positive terminals on both batteries together with a wire, then do the same thing for the negative terminals.

We have wired a few RV batteries together and know our stuff when it comes to electrical connections. We’ll show you the ins and outs and give a detailed description of what to do in order to have connecting batteries that provide you the power you need.



Wiring Basics

When it comes to wiring RV batteries, there are a few things you need to keep in mind. In this section, I will cover the tools and materials you will need, as well as some safety precautions you should take.

Tools and Materials

The tools and materials you will need to wire RV batteries together include:

  • 6-4 AWG copper wire
  • Wire cutters/strippers
  • Crimping tool
  • Heat shrink tubing
  • Terminal connectors

It's important to use the proper size and type of wire for your RV battery setup. The recommended size is 6-4 AWG copper wire, with 4 AWG being the most effective as it has the least resistance, making the transfer of power from the batteries more efficient.

Note that the heat shrink tubing and wire cutters might not be completely necessary depending on whether or not the wires you purchase already have exposed ends on them.

Safety Precautions

Working with RV batteries can be dangerous, so it's important to take the necessary safety precautions. Here are some tips to keep in mind:

  • Always wear gloves and eye protection when handling batteries.
  • Make sure the batteries are disconnected before working on them.
  • Never touch both the positive and negative terminals of a battery at the same time.
  • Keep sparks and flames away from the batteries.
  • Make sure the batteries are securely fastened in place to prevent them from moving around while driving.

Wiring Diagrams

When wiring RV batteries, there are two main wiring configurations: parallel and series. Both configurations have their advantages and disadvantages, and it's important to understand how they work to choose the right one for your RV battery setup.

Parallel Wiring Batteries

Parallel wiring connects the positive terminals of two or more batteries together and the negative terminals together. This configuration increases the capacity of your battery bank while keeping the voltage the same.

In parallel wiring, the voltage stays the same, but the amp-hours (Ah) add up. This means that the battery bank can provide more power over a longer period of time.

There is one very important thing to check when wiring lead acid batteries in parallel: Make sure they are the same voltage. You want to wire 2 12v batteries and never a 12v battery to a 6v battery.

How to Wire RV Batteries in a Parallel

Connecting RV batteries in parallel involves the following:

  • Connect the positive terminal of one battery to the positive terminal of the other battery with the wire. The wire could have a clamp or need to be wrapped around the terminal on the other battery. Most batteries will have at least a loop that can be hooked around the positive terminals.
  • Connect the negative terminal of one battery to the negative terminal of the other battery. The remaining positive and negative terminals will be connected to your RV's electrical system.
  • You should have a negative and positive battery terminal remaining on one battery to connect to the RV load wires.

Series Wiring Batteries

As mentioned when describing the parallel series, the series wiring diagram is used almost exclusively when trying to get more power out of a pair of 6v batteries - and shouldn’t often be used to wire batteries of the 12v variety together.

This configuration increases the voltage of your battery bank while keeping the amp hours the same.

How to Wire RV Batteries in Series

  • Start by connecting the positive terminal of one battery to the negative terminal of the other battery.
  • Do the same for the other battery
  • Connect the RV load wires to the respective remaining positive and negative terminals on the batteries. The positive wire will come from one battery and the negative load wire will go to another.

Can I connect a pair of lithium batteries in series or parallel

You could do either one using the same process described. You will probably not find a need to connect a pair of lithium batteries in series though because the voltage is generally high enough.

Parallel over series

Connecting in parallel will assist in charging batteries equally and having them drain in a more cooperative manner that doesn’t leave you hanging with one battery.


Common Wiring Problems

When wiring RV batteries, there are a few common problems that can occur. One of the most common issues is a loose connection. If the wires are not securely connected, the battery may not work properly.


Another issue is corrosion, which can build up on the battery terminals and cause poor performance. It's important to regularly check the connections and clean the terminals to prevent these issues from occurring.

Blown Fuse

Another common problem is a blown fuse. If the fuse is blown, the battery may not be able to charge properly. It's important to check the fuses regularly and replace them if necessary. Check with your RV’s manual to see where the fuses might be located.

Testing the Battery System

If you're having issues with your RV battery system, there are a few tests you can perform to diagnose the problem. One of the easiest tests is to check the voltage of the battery. A fully charged battery should have a voltage of around 12.6 volts. If the voltage is significantly lower, the battery may need to be charged or replaced.

Another test you can perform is to check the battery's capacity. This can be done by using a battery load tester. The tester will simulate a load on the battery and measure how long it takes for the voltage to drop. If the battery's capacity is low, it may need to be replaced.

Finally, you can test the charging system by checking the voltage at the battery while the RV is running. The voltage should be around 13.8 to 14.4 volts. If the voltage is significantly lower, there may be an issue with the charging system.

Will I need to disconnect my battery bank at some point?

You may need to disconnect part of your battery bank in order to connect a battery charger, especially if one of the batteries is dead.

Otherwise, if you are replacing a battery, you would definitely need to disconnect the parallel or series connections and then reconnect them the same way. If we are unfamiliar with the process or are nervous, we recommend taking a picture of the wiring diagram while connecting batteries so that you can reference it later.