Adding Second Battery To RV | How to Add Conveniently?

A regular car can have a single battery and go by with ease. And they do last more than we expect them. 

But for a vehicle like an RV, which you can camp out in the wild for more than one day, the battery won’t last too long. Although you might have solar panels and everything, the appliances will require more and more power. 

So adding a second battery to  RV is the best possible solution. You can wire it in two ways, with a parallel or a Series connection. 

Today we are going to guide you through the process of adding a second battery. 

Adding Second Battery To RV

Process Of Adding A Second Battery To Your RV | Parallel And Series Connection 

The first thing you need to ask yourself before adding a second battery is, why do you want it? Is it because of more power? Or do you want more capacity? If it is more power, you need voltage. And more voltage means a series connection.

If capacity is what you are looking for, then a parallel connection should be made between the batteries. Both connections are stable and won’t cause any harm to your RV. 

1. Connecting A Second Battery In Parallel Connection

Parallel connections are done to increase the capacity, not the voltage. So you won’t get a higher voltage, but better performance and time out of your battery. If you are looking for just that, you can add a second battery to your RV in a parallel connection.

You will need to connect both positive terminals of both batteries with a jumper cable first. Then move on to connect both the negative terminals the same way. Nothing more. The wiring and other fuse and circuits won’t be affected by this. And they will charge and discharge together. But you will have more capacity. 

Even while charging, both batteries will charge together, as one. 

Connecting A Second Battery In Parallel Connection

2. Connecting A Second Battery In Series Connection 

If you are looking to add more voltage to your RV’s power system to run high-end appliances, you need to connect your second battery in a series connection. And obviously, you will get more voltage added to the grid. 

To do that, you will need to connect in a crisscross manner. The negative terminal of the first battery should be connected to the positive terminal of the second battery. Using jumper cables of course. Here is where it gets tricky now.

You will need to connect the open two terminals not together but to your appliance. Directly. This will get you the extra voltage without causing harm to any of the batteries.

Note that crossing the open positive and negative terminals will cause a short circuit and damage both batteries. So stay with just one connection. 

Connecting A Second Battery In Series Connection

FAQs (Frequently Asked Questions and Answers)

How long will 2 12v batteries last in RV?

In normal condition and usage, 12V batteries in an RV last around 2-3 days. So 2 12V batteries will go 6 days roughly. 

When should I add a second battery?

You should ask yourself if you need more power or more capacity before going for a second battery connection. Then think about if you are not getting by with one battery. If you are planning to run a lot of appliances during the winter and want to camp out for longer than 6 days under heavy weather, you will need a second battery. 

Why does an RV have two batteries?

RVs have 2 batteries to conserve power or to give better voltage output. It also depends on the size of the appliances like the motor, stove, heating and air conditioning system. 


Adding 2 batteries can benefit you in both ways. Either it can spike up the capacity, or it can give you more voltage and power. If you are unaware of electrical components and not comfortable working with them, asking a friend or a professional electrician will help you a lot. Also, a mechanic can help you with it too. Be safe, and happy camping. 

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