How To Wire Multiple 12V Or 6V Batteries To Your RV

It turns out that when you are not connected to power, your RV will be using a lot more power and electricity than you actually think. This quick usage of power and electricity requires wiring multiple batteries to your RV.

Every time you turn on a light, every time you are using your water pump, the fan, or the furnace, you will be draining more and more power. And this can be inconvenient for you while you are on the road.

How To Wire Multiple 12V Or 6V Batteries to Your RV

Why To Connect More Than One Battery To Your RV?

Even when you are switched to an LP gas like propane, you will still be using power on a device like your fridge. And this is all no matter what kind of RV battery you are using, and you want to avoid them getting fully drained.

For different batteries, you only really want them to be discharged to a certain level.

For example, if you are using lead acid batteries, these will only get discharged down to 50% before they start to take damage, and then if you are using lithium-ion, these should only go down to 20%.

And, even if you are using a generator, or if you are using a solar panel for charging the batteries each day, you are still going to want stored power so you can use electricity in your RV without risking damage to the batteries.

So, one of the best ways you can add this extra power to your RV is to just add more batteries onto it.

Because of this, we are going to go through how you can add these extra batteries to your RV safely, no matter how many you want to add.

We will separately go through the best way to do this whether you are working with a 12 volt battery or a 6 volt battery.

However, it is worth noting that we are focused on adding 12 volt power to the RV and not making a solar power bank instead.

So, if you want to avoid risking draining batteries with your RV, and want to know how to add the batteries yourself instead of having to rely on a professional, keep reading to get all the information that you will need!

How To Wire Multiple 12 Volt Batteries To Your RV

As we referenced earlier, wiring 12V RV batteries to your RV is actually not as difficult as you would assume, and a lot of people are able to do it themselves even if they assume that they would not be able to.

However, this does not mean it does not require thought, and there are some issues that can arise, but we will cover these and tell you how you can avoid them.

Following this guide you will be able to wire your 12V RV batteries (see also: Guide On Using A RV Battery Disconnect Switch)in parallel the right way so you can balance all of your batteries and help them last longer and work more efficiently!

What You Need

The first piece that you will need for wiring your batteries together is the right wire, and for this process you will want 6 to 4 AWG copper wire.

If you have to choose one, we recommend 4 AWG just because you will experience less resistance and the power transfer will be more efficient between the multiple batteries.

The set up is also going to be a little different depending on the different sizes of batteries you are using and the area you use for storage.

You will want the right length of both red and black 4 AWG copper wire as well as the battery terminal connectors.

One of the best kits you can get to make this process a little more simple is the Windy Nation 4 AWG Wire Kit which will work perfectly with most of your deep cycle RV batteries, and the kit will give you enough wire to work with if you have average connections.

However, if you are wiring more than 4 batteries to your RV or if you know there will be more distance between your batteries, then you will likely want to get more wire.

You will also need a crimping tool as well, it is not a necessity, but it will help you a lot with your terminal connections.

What Actually Is Parallel Wiring?

Something we mentioned a little earlier is parallel wiring, so we think it is worth explaining exactly what that is here.

So, parallel wiring is when you connect your batteries through parallel, so positive is going to positive, and negative is going to negative. This effectively combines your batteries too to make a larger one that will still have the same voltage.

You will not be able to combine batteries that have a different voltage, and we also do not recommend trying to connect batteries that are a significantly different size or age.

There is more information about parallel and series circuitry available, however, we will ensure that you have the main information you need in this guide. But ensure that the voltage is the same when you are wiring 12V RV batteries.

The Way Not To Parallel Connect 12 Volt Batteries

When you are wiring your 12V RV batteries it is important to know the right way to do it and the wrong way. You do not want to have the positive terminals connected and the same thing done with the negatives.

The load wires that are connecting your batteries to your RV are placed on the same batteries, this means that there is excess pressure on your first battery and not enough pressure on the last battery.

This is the incorrect method of using parallel wires in your RVs as it will not balance how you are draining the batteries.

The Way To Parallel Wire Multiple 12V Batteries

It is worth noting that the best and most efficient way to wire your 12V RV batteries is the most difficult way, however, the better results you will get from it are worth it.

All of your 12V RV batteries will be wired to your external battery terminal post instead of just one like in the previous example.

Each of the wires which run from the batteries will need to be an equal length however, otherwise some batteries will be getting more or less resistance than other ones and this will make it unbalanced.

However, there is something that often stops people from being able to do this and this is space.

Not everyone will have enough space in their RV to have more external terminal posts and even though this is more balanced, not everyone can justify the extra space that is used.

However, if you want to make a larger solar power bank using over 8 batteries you will need methods like the one in the example to keep your batteries as healthy as possible, but there are other ways you can achieve this as well.

How To Wire 2 12V Batteries To Your RV

Now if you are connecting 2 12V RV batteries in parallel, this is actually pretty simple and you can find this set up being used pretty commonly.

This is what you will find most RV dealers and manufacturers making room for in RVs. You will want your terminals to be wired in parallel using even lengths of the cable.

However, the main difference between the wiring that is used here compared to the incorrect example is that the load wires you are using from your RV will be connected to different batteries instead of the same one, this balances the circuit and distributes the load properly.

How To Wire 3 12V Batteries To Your RV

Now, once you are adding more than 3 batteries, the method of wiring your load wires can be a little less efficient than in the previous example.

Also, it is worth mentioning that if you are just adding one extra battery, you will also not be getting much difference. However, if you still want to use 3 12V RV batteries then we recommend doing it similarly to the method for 2 batteries.

You will still want to put your load wire on the end batteries and this ensures that the middle 12V RV battery will be getting drawn from evenly.

However, your middle battery will still be putting out fewer amps than the other 2, however, the difference is actually not that much of an issue.

However, if you want to ensure that it is completely perfectly balanced, then try doing the cross diagonal method we are going to explain for the next set up, even if it is a little less space efficient.

How To Wire 4 12V Batteries To Your RV

So, if you are wiring 4 12V RV batteries, then the wiring will simply require a little more effort and time to make it efficient.

You will not just be able to chain terminals like with 2 or 3 12V RV batteries like before as this will create too much imbalance.

The first method we are going to recommend for 4 12V RV batteries is the cross diagonal method as it will keep your 4 batteries perfectly balanced without needing to use a terminal post method.

If you follow the cross diagonal method, it can initially look pretty complicated, however, if you look at different sections in isolation and find practical examples, it is actually not too difficult to fathom.

All you need to start is to connect two pairs of your batteries using a shorter wire, and then take these 2 pairs and connect them using a longer wire.

This will then combine your 2 groups and then you can connect this to your load RV power wires onto your center terminal using both short and long wires.

However, you will want to ensure that both your negative and your positive load wires are connected using different batteries. So, if everything is wired correctly, then your load wires are connected to your middle batteries.

Each of them will have both a long and a short wire which will help balance out some of the resistances to keep your batteries even.

However, you can add a few more connections, and this will create even more balance compared to just using a normal chain connection using load wires on either side.

However, not everyone can use 4 batteries in a row depending on how much 12V RV battery space you have to work with.

Multiple Batteries to your RV

This is why we also recommend using the cross diagonal method in a block if you want to try and be a little more efficient with your space.

This means each of your batteries will still have a longer and a shorter wire connecting it, but it will still be balanced perfectly.

The best method for you will really depend on how much space you have to work with.

This is why we recommend using blogs and forums, and even talking to manufacturers to find people who have RVs like yours, and seeing what methods they have used to see what will work perfectly in the space you are working with.

Of course, the success of this will depend on how popular your type of RV is.

How To Wire Multiple 6 Volt Batteries To Your RV

If you are looking to increase your durability and your total amp hours in your batteries, then using 6V RV batteries to your RV should be a good option for you.

There are quite a few strengths and weaknesses when it comes to working with either 6 or 12 volt batteries when you are working with an RV, however, it usually just ends up coming down to preference. 

However, if you end up going with 6V RV batteries, then the wiring set up you are using will end up being a little different to when using 12 batteries.

You will need to increase your voltage to 12 volts using the batteries since no RV is able to run just using 6 volt power.

This is done by wiring your 6V RV batteries in a series by connecting your positives with negatives and if you do this the voltage will increase, however the amperage will not!

A good way to exemplify this is if you have 2 12 volt 100ah deep cycle batteries for your RV and then you wire these in a parallel and you will get 12 volts still and 200ah.

Then, if you wire 2 200ah 6V RV batteries together using a series, you will get 12 volts from the 2 batteries, but they will still remain at 200ah.

This means that you can use a series and a parallel wiring scheme as a combination when using 6V RV batteries to make it so you can combine over 4 6V RV batteries. This will retain the right voltage but increase your amperage.

One thing to keep in mind is retaining batteries that are the same kind, the same size, and hopefully the same age to get the best results. 

How To Wire 2 6V Batteries To Your RV

As we mentioned earlier, to wire 2 6V RV batteries you will want to combine these in a series so you will end up with a single 12 volt battery.

This can be done using a smaller piece of wire, like the 4 AWG mentioned earlier, the color will not matter though. You can then attach the load wires to power the batteries to one of each of the other batteries.

Make sure to avoid having each of the load wires on one of your 6V RV batteries.

How To Wire 4 6V Batteries To Your RV

Once you know how to wire 2 of your 6V RV batteries in a series to make a single 12 volt battery, knowing how to do this again using 2 more 6V RV batteries is actually not too hard, and this will increase the amp hours.

This can be done by combining a pair of 6V RV batteries and then you will wire them together using a parallel in a similar way to using 2 12 volt batteries.

You will want to ensure that you are connecting your RV power to a different pair of 6V RV batteries to ensure that the batteries stay balanced and last longer.

How To Wire Multiple 12V Or 6V Batteries In Your RV (1) (1)

How To Wire 6 6V Batteries To Your RV

Now, you can make a significant difference by using a big battery bank using 6 6V RV batteries, however, this will start to take up a lot of room, and will weigh a lot.

Because of this, it is not a recommended solution when working in an RV. But in some cases this is necessary, so you will use a similar technique to the previous section.

Your batteries will remain pretty well balanced and the process is very simple as when you are wiring 3 12 volt batteries to each other.

However, like with 3 12 volt batteries, you can use the cross diagonal method, however, it is not recommended for how much extra effort you are going to have to put in for it to work.

How To Wire 8 6V Batteries To Your RV

As you can imagine with how much space it will take us, using 8 6V RV batteries is not the most common set up, however for some people it might be the best option.

You will need to use the cross diagonal method like you would for 4 12 volt batteries, however, this will take up a lot of space so keep this in mind!

Summary

Hopefully this guide has given you the information you need and advice that will be useful when it comes to wiring (see also: DIY Guide: How To Wire A 30-Amp RV)together multiple batteries for your RV.

We recommend that if you want the results to be the best for your RV, that you look online for forums and blog posts related to your specific model of RV so you can see what other people are doing with the same amount of space available as you have.

This will make asking more specific questions easy and you will not have to worry about potential set up differences as well.

Frequently Asked Questions

What AWG Of Wire Should Be Used For RV Batteries?

The best AWG for wiring together RV batteries is 4 AWG. You can also get away with using 6 AWG, however, if you want the best results possible, use 4 AWG.

Where To Connect The Battery Charger For Multiple Batteries Wired Together?

You are going to want the battery charger to be connected to the same battery terminal as the ones which your load wires are connected to.

This will ensure that your batteries will not just be used at an even rate, but also charged at an even rate.

Does Your RV Need 2 Batteries?

The only circumstance where your RV is going to need 2 RV batteries is if you are relying on 6V RV batteries. This is because you are going to need at least 12 volts of power for the RV to work.

However, if you are working with 12 volt batteries, then using just one is fine, however, using multiple will last you longer and you will get longer amp hours.

Can You Mix Your Batteries To Different Amp Hours?

You can not mix batteries that have different amp hour capacities when wiring together 6V RV batteries. When you are wiring in parallel using 12 volt batteries you are able to use different sizes of batteries.

However, do not mix battery ages, do not go further apart than 6 months.

How To Hook Up 3 12V Batteries To Your RV?

Yes, this is possible, and in this guide we have an explanation of how you can do this in a simple way which will drain the batteries equally.

Should You Be Leaving Your RV Plugged In All The Time?

If you are leaving your RV constantly plugged in then you want to ensure that your RV uses a smart or a 3 stage charger using its converter.

There is a chance that if you have an older RV it uses a trickle charger on the converter which can overcharge your batteries.

Eddie Meyers
author avatar
Eddie Meyers
My name is Eddie, and I am an RV enthusiast! I have enjoyed traveling all my life, and want to give my family the same opportunities to see as much of the world as possible. As I’ve gotten older, I’ve discovered how great RVs can be for vacations with a young family. Here at RV Lifestyle Experts, I want to share my experiences, the tips I’ve picked up along the way. I hope that our guides can encourage you to try the RV lifestyle. I promise you that you won’t regret it!
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