For many caravanners, choosing a caravan leisure battery is a simple matter of picking whatever is available in their local dealership. But with a little more thought you get a whole lot more for your money.
What does a leisure battery do?
First and foremost, it powers your 12v appliances, not least your lights, phone charger, cooker, water pump and fridge – not to mention the kettle. It goes without saying it’s an important piece of kit.
But it also has a second job. Being linked up to the main charger of your caravan or motorhome, a leisure battery can also help ensure a regular, uninterrupted and constant power supply. For this reason, it is never advisable to run your appliances straight from the built-in charger.
How do leisure batteries work?
Lead plates are held in diluted sulphuric acid, releasing ions as the metal dissolves and creating an electrical charge. The voltage is increased when the acid is more concentrated. As the electricity runs through the battery, the process reverses and the metal ions re-join on the lead plates.
You can charge a leisure battery in various ways. First and foremost, plug into the mains on a campsite hook up. Use a trickle charger to slowly top up while the battery is being used – but bear in mind this will never re-charge the battery. A split charge relay needs to be professionally fitted and is powered from the alternator providing a charge to the leisure battery until the vehicle battery is fully charged. Lastly, you can use solar power, a technology which is still improving in efficiency and reliability.
Remember that most leisure batteries for caravans and motorhomes will only last around 2,000 cycles (a full charge with a subsequent full discharge). Also, keep in mind the effects of temperature: a warmer ambient temperature allows a leisure battery to hold a greater charge for longer than it would at colder temperatures.
Why do I need a leisure battery?
You’ll need a reliable caravan battery whether you’re hooked up to the campsite supply on a regular basis or more likely to be found off-grid, perhaps on a rally or wild camping. Or more drastically, as sometimes can happen, you find the nearest hook up point just out of reach of your charging cable!
A leisure battery, sometimes known as a caravan battery, is designed to provide a low current over relatively long periods and to be frequently discharged and then re-charged. This is quite different to a car battery.
Different types of leisure battery
The National Caravan Council has a scheme to verify classification of leisure vehicle batteries.
Batteries with greater storage capacity: ideal for those spending time in their caravan or motorhome but not hooked up on a campsite mains.
Category A badge NCC
Ideal for those who are frequently using campsite hook ups, and who need a hefty capacity to enable them to use devices like motor movers.
Category B badge NCC
Batteries with lower capacity: ideal for those who just want to run basic appliances before hooking up on a campsite on a frequent basis.
Category C badge NCC
These standard issue batteries usually have a plastic or polypropylene housing provided with several compartments. Via an ingenious, but simple, combination of meshed lead plates, lead oxide paste, separators and sulphuric acid, electricity is generated: around 12.7v for a leisure battery in full working order.
Since it is not a good idea to spill corrosive acid, some leisure batteries are made for uses during which there is a high chance of the vehicle (and therefore the battery) over-turning. Most common examples might be quad bikes and jet skis. These batteries employ a gel-based electrolyte. Certain motorhomes and campervans are provided with gel batteries which are seen as providing an additional level of safety.
Alternatives include AGM (Absorbent Glass Mat) batteries which use a glass fibre solution. This is widely considered superior in performance but is certainly more costly.
Lead crystal batteries use very little liquid, the acid being crystallised, not liquid. And lithium batteries are much lighter (no lead being present) but are more expensive.
How safe are leisure batteries?
Leisure batteries are inherently perfectly safe – as long as they are properly handled, responsibly used and carefully maintained.
A leisure battery is a heavy item, containing lead. It also contains acid and outputs a mix of hydrogen and oxygen. And it delivers electricity. So respect and care are essential at all times.
The battery should be properly installed so as not to be able to move around – a secure mounting is vital. The gases are usually vented outside via tubing or a ventilated panel. When working with a battery, or perhaps disconnecting leads, make sure no naked flames are present and beware the corrosive effects of the acid (eyes, skin, clothing and so on).
A 12v battery rarely causes electrocution but it pays to have good quality clamps, not flimsy crocodile clips.
An example of verified and categorised battery labelling
Top Tips to getting the best from your leisure battery
- Keep your leisure battery charged up whenever possible – this will extend battery life. Even when not in use the battery should ideally be charged every month or so. If this is not done phosphorus can build up on the plates, hindering the chemical reaction.
- Switch off appliances when not in use.
- Caravan manufacturers and accessory providers offer ‘maintenance free’ sealed batteries which require no topping up with water. Overcharging these can cause problems by reducing the electrolyte liquid. Sealed batteries need to be charged using an automatic or voltage-controlled battery charger which does the job in a measured way.
- Once a year give the battery tray and terminals a wipe, adding a little petroleum jelly to the battery connectors. Check the electrolyte levels are covering the plates (of course, no need if it is a sealed battery).
- When buying, it is generally advisable to buy a caravan leisure battery manufactured within the last year.
- Using a second, back up leisure battery can be tempting on long trips. The second battery will hold its charge and can be simply switched over when the primary battery runs out of power. But make sure you have a suitable, secure and safe space for a second leisure battery.
As with many things in life, you generally get what you pay for when it comes to leisure batteries. Cheap leisure batteries often quickly fail to hold their charge and do not last long. So do your research and ask around. One measure of quality is weight: the heavier the battery, the more lead it is likely to contain, and so the greater the charge it can hold.
That said, a budget battery might be a decent choice for someone who expects to hook up most nights to a campsite mains – the leisure battery in this instance is not the unit delivering the power.
Deciding the best leisure battery for your needs depends on all sorts of factors. The best leisure battery for you will not necessarily be the best leisure battery for the next person. It will depend on usage rates, frequency of hook up, units needing to be powered (and how often) and price of course.