Leisure Batteries for Motorhome

Angie de Sousa

Let us help you tackle the motorhome leisure battery minefield . . .

This article on leisure batteries for motorhomes really tries to keep it simple. It can be really difficult to understand some of the technical aspects of batteries and how they are set up, so I hope this makes it simple for you. We were searching for simple and straightforward information when trying to sort our batteries out, and it was lacking, so we hope that this keeps it to exactly that kind of level. So this is our straightforward guide to volts, amps and charge levels for your leisure batteries for your motorhome.

Firstly, what is the difference between a motorhome leisure battery and a car battery? The key difference (other than size and weight) is that a leisure battery is designed to trickle charge items to provide power, which will charge items over a period of time. A car battery gives a good boost of power immediately in order to start the car. This relates to petrol or diesel cars and not for electric cars.

The Difference Between 12v and 24v Circuits

In a house, electrical appliances run on a 24v circuit. So in the UK, all your electrical goods run from a 3 pin plug, which slot into sockets and are powered by your 24v system. In a motorhome however, everything comes from your leisure batteries, which operate on a 12v system. The 12v system is much more efficient than the 24v, but it does mean that if you want to use your household appliances in your motorhome or campervan, you will need to be ‘hooked up’ or on ‘EHU’ (electric hook up).

Can I Use My Electrical Appliances on Electric Hook Up?

If you are hooked up to an EHU then you are able to use the plug sockets that you probably have placed around your motorhome. These are powered because the circuit has access to a higher voltage via the EHU that you are hooked up to. If you are not hooked up to the EHU then none of these sockets will work. If you are off grid, and are running a generator, then the generator mimics being hooked up and all of your sockets will work still.

What is an Inverter?

An inverter is a piece of electrical equipment that swaps converts the direct current (DC) to an alternating current (AC). You will hear the term DC2AC when people are talking about electricity in vans. An inverter is one of the tools that help to do this. It takes the power from your battery, which is 12v, and converts it to the power that your appliance has been made to operate on, which is 24v.

Do I Need One to be Off Grid?

If you want to be off grid and want to use electrical appliances which have a 3 plug, maybe a laptop charger or something similar, then you will need an inverter. An alternative to an inverter could be that you have a big powerbank like a Jackery. These are probably the best powerbank you can get to support your motorhome travels, but they are expensive. You might ask yourself whether you are best placed to invest the money in upgrading your batteries that are permanently in the motorhome.

Basic Battery Terminology

There are some terms that you will come across when looking for your new leisure batteries for your motorhome. So I will cover what they are too.

Amp Hours (AH) – This is how much current they have in them and can output overtime. It doesn’t mean that it has 100 hours of use in the battery as something like a 1200 watt kettle might use almost 6 amp hours in just a 3 minute boil.
Discharge Capacity (or Depth of Discharge) – This relates to how much energy you take from your battery before you charge it again. When we talk about ‘discharging a battery to 50%’, it means that you have used half of the batteries electrical capacity.
Efficiency – Batteries take some power to charge and discharge and the amount of power used varies amongst battery types. A lead-acid battery is 80-85% efficient whilst a lithium is about 96% efficient. For example, if you take this from a practical perspective, if your solar panel can produce 500w of power, the lead-acid will store 400 watt hours, and the lithium can store 475 watt hours due to its efficiency capability.
Cycle – Every time a motorhome leisure battery is charged and discharged, that equals one cycle. How many cycles a battery has is a better measurement for true battery life, not time.

Voltage vs Charge Levels On Your Motorhome Battery

We use to read our battery and see it sitting at 12.2 and think ‘Hmmmm, is that good or bad?’. We knew less than 12 was not great, so we used this handy reference guide which will help you to understand roughly how much power you have in your battery.

Different Types of Motorhome Leisure Battery

It can take quite sometime to get your head about the differences on motorhome leisure batteries. When you got your motorhome, you were probably a bit like us in thinking ‘well, its got a battery so that’s good’. In fact when you are buying your first motorhome, you don’t really think about these things, and the reason for that is that you simply just don’t know its a think you need to think about!

In the UK in winter and other countries that are in the north of the northern hemisphere, having enough juice in your battery can be a never ending battle. If you are not on EHU, then this is going to be a key element of your fulltime motorhome living lifestyle or its is going to be very important for that week of wild camping that you want to undertake.

Motorhome Leisure Batteries Overview

There are 4 main types of leisure battery that you can buy for your motorhome:

Wet Led Acid Battery
AGM Battery
Gel Battery
Lithium Battery

For the purposes of this post, I am taking 110 ah battery size as they tend to come as the standard fit in new motorhomes and campervans. It was also what we first had in our motorhome.

'Wet' Lead Acid Motorhome Leisure Battery

The Wet Lead Acid battery is the most basic battery option that you can have as a motorhome or campervan leisure battery. The battery uses lead-acid technology and contains lead plates in liquid electrolyte which contains sulphuric acid. There are two main types – ‘open’ and ‘sealed’. Both variants of the wet lead-acid battery are suitable for those who require to go on electric hook ups (EHU).

A lead-acid motorhome leisure battery can be discharged to 50% before you start to actually damage the battery and impact its lifespan. It is the entry level battery choice and the cheapest. The ‘sealed’ one is the zero maintenance option.

DISCHARGE LEVEL: 50%

LIFE CYCLE: 200 charges

PRICE POINT: £140

AGM Motorhome Leisure Battery

The AGM battery does not require ‘topping up’ and can be discharged to 50% before damage is done to the battery itself. Instead of using a wet electrolyte it uses absorbent glass mats, which is where the name AGM comes from. This provides better protection from a safety perspective than the lead-acid batteries.

The AGM motorhome leisure battery is also maintenance free. The price point is higher than that of the basic lead-acid battery option and it is from a safety perspective. The actual performance is no better than the lead-acid but they do have lower levels of self discharge, which is how they run down when just standing there not being used.

DISCHARGE LEVEL: 50%

LIFE CYCLE: 200 charges

PRICE POINT: £240

Gel Motorhome Leisure Battery

A gel battery is ‘leak proof’ and can discharge to a lower level than an acid battery without doing damage. The other thing with gel batteries is that you can install them on their sides without risking them leaking. This could be a benefit when considering space, especially in self-builds where you are able to configure this yourself.

Gel batteries are sensitive to over charging, so you need to configure your PWM or MMPT according to the instructions given by the manufacturer. A gel can discharge up to 80% compared to the 50% of an lead-acid or AGM battery. This makes them favourites for ‘wild campers’ due to the amount of electricity you have available to use in the battery. Of course this all comes at a price.

DISCHARGE LEVELS: 80%

LIFE CYCLE: 500 charges

PRICE POINT: £280

Lithium Motorhome Leisure Battery

The lithium battery, commonly known as the LiFePO4 battery. It is the king of kings of motorhome leisure battery power. There are several benefits for lithium batteries; the amount of the batteries energy that you can use, the lower weight of the motorhome battery compared to its counterparts, the speed that the battery takes to recharge and the fact that it doesn’t damage when it is left in discharged state.

This is the battery that we have now. We started with the AGM, then moved to Gel and finally decided that for fulltime motorhome living, the lithium batteries were what we needed. And I do not regret that decision for one second. We did a lot of research into where to get the lithium battery from as we were very conscious of Chinese imports. As we didn’t have the skill to build our own, it was important that the battery was just a lift and replace option. We came across a company called Fogstar. We purchased the 300AH lithium batteries, but you can buy the 105 ah lithium motorhome leisure battery for just £369+ VAT. An incredible price. Places like Tanya batteries (who we had previously used) charge at least 3 times that price.

DISCHARGE LEVEL: 95%

LIFE CYCLE: 2000 charges

PRICE POINT: £1000

How To Calculate Your Electricity Usage.

In order to help you understand what kind of battery type and size you need, you need to work out how much battery power you need. This whole process can be very confusing and I will endeavour to make it as simple as I can.

You need to think about all the things that you will be powering up in your motorhome and then seeing how many watts that equates to.

Find Out Your Watt Hours

A simple calculation might be:

TV rated at 100w on for 4 hours in the evening: 100 x 4 = 400 watt hours

4 light bulbs rated at 20 watts for 4 hours: 4 x 20 x 4 = 320 watt hours

Water pump rated at 50w per hour – 1 x 50 = 50 watt hours.

The total of all the electricity being used is 770w. You should add in a 20% safety margin which will bring this total up to 924 watt hours of total usage per day. This is the first part of the calculation.

Calculate Electricity Hours In Your Battery

The second part of the calculation is to understand how many hours of electricity your battery holds.

To understand this, if you take the amp hours (in this post we have used 110AH as our standard), and divide it by the voltage of the motorhome (12v system) you know how much your battery will hold .

An example would be:

110ah divided by 12v = 9.16 hours of electricty.

So now you know how many hours of electricity you use (you should calculate this for per day) and you also know how much one 110ah motorhome leisure battery will give you.

Motorhome Leisure Battery Electricity Usage Results

The final part of the equation you need to work out is this:

My amp hours usage calculation results:

924 watt hours divided by 12 (my motorhome voltage system) = 77ah per day.

You will need 77 amp hours of electric available to you to run your TV for 5 hours, your 4 lights for 4 hours a day and have the water pump on for filling up the kettle for your TV tea breaks.

If you have a single leisure battery of 110ah, of which only half is useable, then you can easily see from this calculation that you are going to struggle. Don’t forget you haven’t charged up any phones, put a radio on to listen to or put the hot water heating on to do the dishes yet. It really is surprising how much electricity we use.

Leisure Batteries for Motorhomes Summary

We haven’t gone into extreme depth on our motorhome leisure battery article, because we don’t think it is necessary to enable you to make the decision on what kind of motorhome leisure battery that you need to buy. The key points are hight-lighted and how to calculate your own usage is also provided.

The best piece of advice we could possibly give you it to get the best leisure battery for your motorhome that you can afford. The leisure battery for your motorhome is your storage bank.

The more Amps (AH) you have in your battery – the more electricity you can store.
The better quality the battery, the more electricity you can use, without doing any damage to the battery (the discharge).
The lithium battery really is your best battery as it recharges the quickest as well as allowing discharge to the lowest volume.

The final piece of the puzzle that of course you need to note, is that you will probably have a solar panel or something which is topping up your motorhome leisure battery in the daytime. On overcast days and winter in the UK, where rain is a common feature, you will get nothing coming in from your solar panels, maybe just a few watts. And this is where you can find yourself running in to difficulty.

We hope you enjoyed this article and found it useful. If you found it useful, please do share with others using the share buttons below. If you think we have missed something – please do let us know. We read all our emails!

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Leisure Batteries for Motorhome

Let us help you tackle the motorhome leisure battery minefield . . .

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The Difference Between 12v and 24v Circuits

Can I Use My Electrical Appliances on Electric Hook Up?