How to charge a leisure battery

A leisure battery is an important feature for campervan and caravan owners, and ensuring yours is charged means you’ll be able to use your appliances when needed.

In this guide, we’ll discuss what a leisure battery is and highlight some different leisure battery chargers. We’ll also look at simple steps for using some of the most popular options, how long it takes to charge a leisure battery, and where to buy one.

What is a leisure battery?

A leisure battery is a deep cycle 12V battery designed to provide a steady supply of power over a long period rather than in short bursts like a car starter battery. They’re commonly used in caravans, campervans, boats, and off-grid setups to power lights, fridges, pumps, and other appliances.

Different leisure battery chargers

There are many types of leisure battery chargers, and the right one for you will depend on your vehicle and the power source available. The main types include:

• Mains chargers: These plug into the mains power supply at home or on a campsite and convert AC to the correct DC voltage for charging your battery.
• DC-DC chargers: Used to charge the leisure battery from the vehicle alternator while driving.
• Solar charge controllers: Used between a solar panel and leisure battery and works well for off-grid charging.
• Combined units: Some caravans and campervans use an all-in-one charger/power distribution unit.
• Trickle chargers: Low-amperage chargers designed to maintain full charge during storage.
• Inverter/charger combinations: These combine a mains charger with a 230V inverter allowing charging from mains when plugged in and drawing 230V power from the battery when off-grid.

Charging a leisure battery

Before charging your leisure battery, you’ll need to:

• Identify your battery type: Different leisure batteries need different charging voltages and methods. Check your battery or its manual to find out what type you have.
• Choose a charging method: There are several charging methods to choose from, including mains charging (at home or using a hookup), alternator charging (using your vehicle’s engine), or solar panel charging (great for off-grid adventures).
• Stay safe: Disconnect loads before charging your leisure battery if possible, and charge in a well-ventilated area.

How to charge using a mains charger

• Disconnect any 12V appliances or loads from the battery.
• Make sure your charger matches your battery type.
• Connect the charger to the battery (red clamp to battery positive terminal and black clamp to battery negative terminal).
• Make sure the connections are firm and not touching each other.
• Plug the charger into the mains socket and switch it on.
• Most smart chargers will start automatically and show charging progress.
• When charging is finished, the charger usually switches to float or maintenance mode.
• Turn off the charger and unplug it from the mains.
• Remove the black lead first, followed by the red lead.
• Once charged, reconnect 12V circuits or devices.

How to charge using the vehicle’s alternator (while driving)

• Make sure the leisure battery is properly installed and securely wired to the starter battery via a relay or DC-DC charger. Never connect batteries directly without one as it’s unsafe and can cause damage.
• Turn on the engine. The alternator will begin charging the starter battery first.
• When the starter battery reaches a set voltage the split-charge relay or DC-DC charger will automatically connect the leisure battery.
• Leisure battery charging begins automatically.
• Drive for several hours and the alternator will provide power to both batteries.
• When you switch off the engine, the relay or DC-DC charger will disconnect the two batteries, preventing the leisure battery from draining the starter battery.

Read our guide on 'does my car insurance cover towing a caravan?' for everything you need to know before you hit the road.  

How to charge using solar power

• Place or mount the panel in direct sunlight, away from shade and angled toward the sun.
• Connect the controller to the battery first (red from the controller to positive on the battery and black from the controller to negative on the battery).
• Most controllers will light up or show a solar symbol once power is flowing.
• Charging begins automatically.
• The controller regulates voltage and current to safely charge your leisure battery.
• You can monitor voltage or battery level on the controller’s screen or LEDs.
• To disconnect, remove the caravan solar panel connection first, then disconnect the controller from the battery.

How long does it take to charge a leisure battery?

The charging time of a leisure battery depends on several factors, including battery capacity, charger output, battery type, how much charge is needed, and charging method. For example:

• Mains charger: Charging a 100Ah battery from empty to full using a 10A smart charger will take 10 to 12 hours. If you use a 20A charger, this will take around six hours.
• Alternator charging (while driving): A modern alternator typically outputs 10 to 30A to the leisure battery through a DC-DC charger. A basic split charge relay will take between 12 and 24 hours to charge a 100Ah battery while a 30A DC-DC charger will take four to five hours.
• Solar charging: Charging a leisure battery using solar power is slower than other options and weather dependent. It will take between 24 and 30 hours of sun exposure to charge a 100Ah battery using a 100W solar panel and between six and eight hours for a 400W panel.

Where to buy a leisure battery

One of the best places to buy leisure batteries is tyre and auto chains, such as National Tyres and Autocare, which stock leisure batteries and can order what you need, and Kwik Fit that offers a convenient click & collect service for leisure batteries. Car, motorhome, and caravan specialists are another great option. Euro Car Parts stocks various leisure battery brands, KS Energy UK specialises in lithium battery solutions, and Battery Group is a specialist battery supplier with AGM, gel, and lithium options.

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