When do you need a leisure battery?

If you’re a long-time owner of a campervan or motorhome then you’re likely familiar with the world of leisure batteries, but if you’ve never dabbled before then you may be wondering what they’re all about.

A leisure battery is essentially the same as a car battery, they both provide 12v power, but it has a significantly different purpose and design.

Let’s start by first clarifying what a leisure battery actually is.

A ‘vehicle battery’ – those used to actually start cars and motorhomes – is still a 12v battery with a certain ampere hour (Ah) rating, but its chemistry is designed so that it can provide a large amount of power in a short amount of time. That’s because an engine needs a large draw in order to start up – as much as 400A for a standard-sized engine! Once going, however, the battery is soon recharged by the vehicle’s alternator.

A leisure battery, on the other hand, is much the same but is instead designed to power the 12V equipment found in a campervan or motorhome – think of things like the lights, the fridge, power sockets, or a TV. These are usually physically larger than vehicle batteries as the important consideration for them is capacity. Because motorhomes and caravans often go ‘dry camping’ – camping without access to mains power – the leisure batteries need to power lights and appliances for long periods of time. These appliances taken all together usually have a low amp draw – as small as 20A with everything running at full power.

The capacity of a leisure battery is usually specified in terms of a ‘C’ number. What’s listed as, say, a “210Ah” battery is usually a C20 rating, meaning that over twenty hours the battery will be able to supply 210Ah of power. This matters because larger draws over smaller periods of time create significantly more heat, which means that energy is lost through that heat. It’s important to remember, however, that discharging your leisure batteries too low will significantly decrease their lifespan.

Types of leisure battery

Any battery used for things other than powering a vehicle’s engine can be classed as a ‘leisure battery’. The different types, however, have different capabilities.

Flooded lead-acid batteries: are the oldest battery technology, they operate by charging an area flooded with an electrolyte (a mixture of water and lead acid). They tend to be cheaper but require a lot of space and monthly maintenance for larger capacities. They also need to be mounted upright to stop them leaking.

Sealed lead-acid batteries: these are essentially the same as flooded batteries but are sealed to stop leaks. They come slightly more expensive than flooded batteries but the lack of required maintenance is often worth the price for many buyers.

Absorbent Glass Mat (AGM) batteries: AGM batteries suspend the electrolyte in thin, glass mats. They’re zero-maintenance like sealed lead-acid batteries but have the added benefit of being resistant to vibration and movement. As lead-acid batteries are filled with the liquid electrolyte, prolonged movement can affect their performance and charging, this isn’t the case with AGM batteries.

Lithium-based batteries: this is fast becoming the holy grail of leisure batteries due to their tiny size, huge capacities, and impressive charge and discharge rates. Many batteries based on lithium chemistry also don’t suffer the same lifespan reduction with deep discharge. So you can run them until they’re empty without worrying about affecting their life-cycle.

Looking after your leisure battery

If you have a leisure battery in your campervan or motorhome, or have now realised that you’re going to need one, then there are some tips and tricks you can follow in order to get the most out of it.

Make sure that you keep your battery at a suitable level of charge, as a consistent discharge and hefty recharge can dramatically reduce its lifespan. Discharge over a period of time can cause sulphation to occur, involving sulphur crystals forming on your battery plates. However, overcharging can cause the same plates to break down through overheating, so it’s important to get the balance right.

Each battery will come with its own data sheet that explains discharge cycles and their effect on your particular battery’s life. Look at the “C20” rating and try to not discharge your batteries past the amount specified. As a good rule of thumb, keeping your batteries charged above 50% will double their lifespan.

If your caravan or motorhome is likely to be unused for a long period of time, then you should try not to forget to care for your battery during this time. Otherwise, you may come to use it again and find that it’s no longer working. A trickle charger can be a big help at ensuring that your battery maintains some life during the time it’s not in use. Many modern ‘smart’ chargers are able to discern the type of battery, charge appropriately, and hold a maintenance charge, so that you don’t have to worry about checking up.

If you have an old battery, consider getting it replaced if it's been in use for more than a few years, as most batteries will no longer be effective after approximately five years. However, the lifespan of a battery depends on many factors, including how many appliances it’s having to power. If you’re having to recharge your battery a lot due to increased use, then you may find that it degrades sooner.

Replacing your leisure battery at Kwik Fit

At Kwik Fit, we stock Flooded and Absorbed Glass Mat (AGM) batteries to ensure that whatever leisure battery you need to get your campervan or motorhome back to its best, we can help. Find out more about our leisure batteries, or get in touch with your local Kwik Fit centre to see how we can help.