When I was setting up my motorhome I had no idea how many batteries I would need. Other than knowing I needed a deep cycle battery, I didn’t know much else about buying an RV house battery. I started off on a budget, buying two at a good price from contacts in the automotive industry. Over time my power needs grew and I now have a total of five batteries set up as three different battery banks. See how I set up my electrical system here. If you’re looking at buying an RV house battery, the number you need will depend on many things.

Batteries are expensive and this may be a limiting factor for some people. Another thing to consider is how often you will be using them. Is it for the odd weekend away, a couple of weeks at a time, or do you live in your motorhome full time? You need to think about what your power needs are going to be, although the problem with this, as was the case for me, is that over time your power needs might grow.

Your batteries are storing the power that you want to use. That means that you need enough to get you through the times when you have no battery charging capability – overnight if your batteries are charged by solar. This might be longer if you have a period of bad whether when your solar charging capabilities are limited by cloud.

So if you’re buying an RV house battery, how many do you need? Assuming budget isn’t a factor, it’s a good idea to buy as much as you can (within reason) and solar panels to match. (enough solar to top up your batteries daily) It’s good to know you have enough battery power and solar panels to not have to worry about your power usage. Check out this article if you’re wondering how many solar panels you should have.

The RV house battery set up in my van

As a guide, in my small van I’ve been using 200 amp hours of Lithium (12 Volt) and a 270 watt solar panel. This is running lights, a small Waeco 40 litre fridge, a laptop computer most of the day and charging two phones. The most I’ve seen the batteries drop is to 70%, meaning I’ve used 30% of the 90% capacity when using lithium batteries.

The RV house battery set up in my motorhome

In my motorhome I have three different battery banks. 100 amp hours of lithium bought from Sunny Tech Solar at 24V is powering the 255L Samsung Fridge and water pump. 200 amp hours of AGM at 12V is powering lights, stereo, laptop, monitor, charging phones, and the diesel heater. 100 amp hours of AGM is being used for charging small items, lights, cigarette USB items, spark for the gas oven, spark for the gas hot water.

The minimum amount of RV house batteries I’d want to have

As a minimum I’d want 100amp hours of lithium in a small van, and in a motorhome or RV I’d want 400amp hours of lithium. If you’re installing AGM batteries or similar, you pretty much want to double the amp hours of the lithium. So 200amp hours of Lithium minimum in a small van and 800amp hours of AGM in a motorhome. Read more about how to choose house batteries for your motorhome or RV here.

Use a formula to calculate your power needs

There are more scientific methods you can use- formulas to work out your power consumption. The idea as that you buy your RV house battery to suit your exact power needs. Work out everything you want to be powering in your motorhome, use the formula to see how much power they are going to use, and then buy your RV house battery and solar panels to match this number. Thats fine, assuming you already know what you’re going to use, your power needs don’t increase over time, and you’ve factored in the weather conditions, where in the world you are (daylight hours are location dependent) and know how long you’re going to use each item daily.

Gather ideas from other motorhomes, RV’s or vans similar to yours

My suggestion is to talk to people with motorhomes, RV’s or vans, similar to what you own or are building, ask them what sort of RV house battery they have, find out how it’s been for them, how many they have, and what powered items they use in their vehicle. It’s really worth getting to know a bit about the house electrical system in your motorhome, that way if you’re camped in the middle of nowhere and something fails, you’ve at least got a chance of restoring power yourself. This all assumes you’re working with 12 volt or 24 volt power supply. Not mains power.

How to Charge RV House Batteries

Solar panels are a great way to charge your RV house battery. The sun is providing you with free energy every day. Even on cloudy days your solar panels will still work. The output will be reduced, but as long as there is light you’ll get a small amount of charging. If you think you’ll be worried about charging on cloudy days, add an extra solar panel. Instead of 1amp of charging from the panel, adding a second panel would double it to 2amps on a cloudy day.

Although not a preferred option by many due to the noise, you can use a generator to charge your batteries.

How to Charge Your RV House Battery While Driving

You can charge your RV house battery using the vehicles alternator while driving. A device called a voltage sensitive relay (VSR) is used to allow charging of the vehicles battery and the RV house battery at the same time. When the engine battery reaches 13.7volts the VSR allows charging of the RV house battery. When the engine is stopped, the voltage drops and the VSR disconnects the RV house battery from the vehicle start battery. This protects the RV house battery from voltage spikes when starting the vehicle and prevents the vehicle start battery being inadvertently drained.

Gel, AGM and Lithium batteries all have different requirements for charging. You need a charge controller that you can input the correct charging settings for your type of battery. This is pretty simple to do on most charge controllers. If you’re using lithium batteries, make sure your charge controller supports their special charging requirements. See more about my charge controllers here. I look at the EPEVER charge controllers and the EPEVER Solar Station Monitoring software.

My RV House Batteries

I began my journey into RV house batteries knowing very little about them. Like most people, I knew they were something I needed in my motorhome although other than needing deep cycle batteries, I didn’t know anything about amp hours, the different types, how to use them, or what I really needed. I was on a tight budget so I also needed to get something that was relatively cheap. I started off getting two 90Amp hour deep cycle batteries, discounted at a good price from people I knew in the automotive industry. I connected these in parallel which gave me 180 amp hours at 12 volts.

As my power needs grew I bought a second battery. A 100 Amp hour 12 volt AGM battery which I also bought a small charge controller and solar panel for. I needed to get another charge controller and solar panel as you shouldn’t connect different types of batteries, or batteries at different stages of their life.

Finally, I wanted to run a household fridge on an inverter full time. I invested in Lithium batteries. I bought two Lithium Valley batteries. 100 Amp hours each at 12 volt and I have them connected in series giving 100 Amp hours at 24 volts. I plan on doing a full review of these batteries which I bought from Sunny Tech Solar soon! Read more about my electrical set up here.

Why Do You Need RV House Batteries?

Your vehicle has batteries, so why do you need to go out and buy extra batteries? The short answer is – you don’t.

But, there are so many reasons why you would want to get RV house batteries. To start with, the battery in your vehicle isn’t designed to power the appliances you would use camping, out in your RV, motorhome or van life. The battery in your vehicle is designed to supply a high current for a brief time to turn over the starter motor in your vehicle, and it’s then charged by the vehicles alternator.

RV house batteries are deep cycle batteries. They’re built to handle a deep discharge, meaning that you can use a lot more of the battery capacity, over a long period of time, charge it up again, and repeatedly do this without damage to your battery.

You might think of it as your car battery being a sprint runner, and your deep cycle battery being a marathon runner. The car battery delivers a high current for a brief period of time, whereas a deep cycle battery delivers a lower current but for an extended period of time.

So to summarize this question, you need RV house batteries because the battery in your vehicle is not designed to power the house lights, TV, or charge devices in your van or motorhome. You can do it, but you’ll be replacing your vehicle’s battery much sooner than expected.

Benefits of Having Separate RV House Batteries

Not only will it save you needing to replace your vehicle’s battery early, there are many other benefits to having RV house batteries.

You’re using the right type of battery for the purpose so it’s going to last and you’ll get your monies worth from it. A good deep cycle battery should last you at least six years depending on how you use it and care for it.

With dedicated RV house batteries you can monitor your power usage, charge them with free energy from the sun, and power the appliances you’d want in your motorhome.

Keeping your house battery and vehicle battery separate means that there’s no chance of waking up to a flat battery in your motorhome and not being able to start it.

The Different Types of RV House Batteries

Within the deep cycle battery category there are different options available.

Flooded Lead Acid batteries

Flooded Lead Acid batteries are the oldest of the options. They have lead plates that are submerged in an electrolyte mix of sulfuric acid and water. Because of this they need to be installed upright in a position where they cannot fall over and spill dangerous chemicals. They need to be outside your vehicle or in a ventilated space as they give off dangerous gas when they are charging.

Absorbent Glass Mat (AGM)

The Absorbent Glass Mat (AGM) battery is a type of Valve Regulated Lead Acid (VRLA) battery. They’re constructed from thin fiberglass mats placed between the lead plates. The fiberglass mats absorb the electrolyte and act as a damper between the plates. These batteries won’t spill any liquid, they’re sealed, and can usually be installed in any position.

Gel batteries

A gel cell battery is another of the VRLA batteries similar to the AGM battery. The electrolyte, sulphuric acid and silica is mixed together and becomes a gel like substance. Like AGM batteries, gel batteries can be installed in any position, they won’t spill and are maintenance free. They don’t give off dangerous gas like flooded batteries so can be installed inside. Both AGM and Gel batteries have better resistance to vibrations – the gel make up of the battery tends to absorb extreme vibrations in contrast to a wet cell battery.

Lead Carbon batteries

Lead Carbon batteries are a new type of VRLA lead acid battery. They use a common lead positive plate (anode) and a carbon composite negative plate (cathode). Lead Carbon batteries are supposedly a step up from AGM and Gel batteries and often seen as a rival to LiFePo4 (Lithium) batteries.

LiFePo4 (Lithium) batteries

Lithium batteries offer many advantages over AGM and Gel batteries. Although the initial cost is much more than AGM and Gel batteries, the cost is offset by the longer lifespan of Lithium batteries. Lithium batteries are safe to install inside and in any position. They are much lighter in weight than traditional batteries which is good for small van conversions or any situation where you need to give consideration to the vehicle weight. Most lithium batteries can be discharged 90 percent. Lithium are much faster to charge than other deep cycle batteries. Whereas traditional batteries may take most of the day to recharge, your lithium batteries can be recharged by mid morning on a sunny day.

Best Type of RV House Battery

The best type of battery to use as your house battery is most likely dependent on your budget and how you intend to use your motorhome. AGM and Gel batteries are great for those on a lower budget. In my opinion, the ultimate battery if you can afford it is to install Lithium batteries. Lithium batteries tend to be more expensive, but again, they’re worth it. If you’re wondering how many you’d need, read more about that here. They offer so many benefits and are really worth the investment especially if you live full time in your vehicle. Lithium batteries charge fast and soak up any energy the sun throws at them from your solar panels. Wondering how many solar panels you then need? Check out our article about solar panels here.

All the information on the internet about how to set up an RV power supply for your motorhome or van can leave you feeling overwhelmed.

There are many different ways your electrical system can be set up and so many different components, brands, and recommendations. I found it helpful to look at what other people were using in their campers and I was then able to get an idea of what I might need. The perfect RV power supply set up for your camper will come down to the needs of each individual. What do you intend to power? How often will you be away in your camper, or are you living in it full time? How much money do you want to spend on it all?

A Small RV Power Supply Set Up

I had decided I wouldn’t need much in the way of solar panels and batteries and would have very little power usage. My RV power supply would be for a little portable chiller, a few lights and charge my phone and laptop. I purchased two 12 volt 100 amp hour batteries and a 150 watt solar panel with a PWM charge controller. Very basic.

RV Power Supply Needs Grow…

Over time my RV power supply needs grew. I added another battery and solar panel. It’s not recommended to mix new batteries with old batteries or different types of batteries. So I now had two solar systems set up. This wasn’t the ideal way to set up an RV power supply but it worked for now.

And then I went even bigger. I had moved in and was living in my motorhome full time. I now have every thing I could want in the motorhome and as such my power needs had grown.

The motorhome now has three different electrical systems with solar panels and batteries for each. Check out more about how to choose batteries for your electrical set up here.

System One

2 x 12volt 100Amp/hr batteries for a total of 200 Amp/hrs.

2 x 150W solar panels

1 x 30A PWM charge controller

I use this for the lights, diesel heater, and an 1100W pure sign wave inverter. This powers any 240V mains appliances such as laptop and monitor.

System Two

1 x 100amp/hr AGM battery

1 x 90 watt solar panel

1 x 10A EPever solar charge controller

This is powering the car stereo and 12V cigarette lighter sockets for USB charging of devices, and items like the gas hot water heater and gas oven get their spark from it.

System Three

2 x 100 amp/hr Lithium batteries. 100Amp hours @ 24V

2 x 370W solar panels

1 x 40A EPever solar charge controller

These power the water pump and Samsung Digital Inverter fridge

This isn’t the most cost effective way to put an RV power supply system together for your motorhome. I wouldn’t recommend it, but sometimes this is simply what happens. Over time you realize you really want to run more electrical items on your travels. If you’re wondering how many solar panels you really need, check out this article here. Most of my electrical components were bought from Sunny Tech Solar.

EPEVER Solar Station Monitor

I use the EPEVER Solar Station Monitor software on my laptop. It’s a great way to adjust charging settings and to monitor your solar input and loads. It’ll run on old laptops, or at least it runs OK on my old Windows 7 laptop.

You’ll need to buy a special cable that connects from the EPEVER charge controller to your USB port on your laptop. It’s called an EPEVER PC Communication Cable CC-USB-RS485-150U.

The image below is a snapshot of my system at this time… Blue line = power I’m using, Red line is the power from the sun, Green line is what’s going into the battery. This is 200amp hour lithium battery at 24Volts and 780W of solar. It’s a 24V system.

It shows a time period between about 2.15pm and 2.45pm in this picture. The load (blue line) starts out at just over 2amps. That’s my laptop I’m using which is also charging. The load (blue line) increases to just under 4 amps which is where I plugged my mobile phone in to charge. The next increase which takes the load to almost 5 amps is where the Samsung 255L fridge cycles on. The big spike up to 8 amps briefly is the water pump – tap being used.

The red line is what I’m getting from the solar panels. The batteries are pretty much full, and on a float charge so the green line – what’s going into the batteries is maintained by the charge controller at pretty much zero.

One downside of the EPEVER system is that you don’t really know what your solar panels are putting out in the way of amps UNLESS your batteries are way down and soaking up the sun power. In contrast, I have an old PWM controller on which the display shows exactly what you’re getting from the sun – perhaps 12amps, and the next screen shows 2 amps actually going into the batteries. (or similar figures)

See more about my charge controllers and the EPEVER Solar Station Monitor here.

Pros and Cons of Three RV Power Supply Systems

I like having each separate system though. It gives redundancy, meaning if something breaks in one of them I still have power. Eventually I’ll reduce it from three systems down to two. I definitely recommend using Lithium batteries. The motorhome is well equipped for electrical needs. I don’t ever find myself running low on battery power or having to conserve power usage. I’m able to do all the normal things, I charge two cell phones daily and run a laptop and monitor all day every day. I’ll put the stereo on and use all the lights at night. It’s like living in a little apartment on wheels and the power is provided by the energy from the sun. With the combination of batteries and solar panels on the roof of the motorhome, I never have to worry about how much power I’m using. Even in the winter after a few cloudy days, I still have enough in the batteries. The solar panels will generate enough power even on cloudy days to keep the batteries from getting too low.

RV Power Supply Set Up for My Van

My van is a much simpler set up.

I have one 270watt solar panel, 200amp hours of Lithium battery at 12V, a 40 Amp EPever solar charge controller, and an 1100watt pure sign wave inverter. I run a little Waeco 40 litre fridge, and charge the laptop and mobile phone all using the inverter. Lights are 12V LED strip lights. I have a diesel heater for the winter, and these draw high amps on start up for a short time.