Caravan Electrics - Batteries Explained

Leisure batteries and car battery's - what's the difference??

A car battery is designed to give out a large amount of power in a short space of time (starting the car) and then being quickly recharged.  A leisure battery on the other hand is designed to store power and release it over a much longer period of time.  Undoubtedly you can use a car battery in your caravan but it is unlikely to work very well in the long term.

Where to buy

It is not easy to get batteries by mail order due to the acid content and weight.  As such we recommend buy from a reputable caravan dealers

Checking a caravan battery

This helpful video shows how to check a caravan battery.

How big?

Caravan Batteries are available in different sizesBattery power is measured in amp hours.  The higher this number is the better as this gives you an idea as to how long it will last.  Generally, leisure batteries are available from 75amp hours to 110amp hours.  A common question is how long will a leisure battery last for caravanning.  The obvious answer, is unhelpfully, depends how you use it and what for.  To give you an idea as to consumption of caravan equipment running on battery we have prepared a chart for you to add up how much power you need.


How long will a battery last in reality

If you followed this consumption pattern and ran a 110 amp hour battery to total discharge you would it would last just under two days.  However, in reality you would not get this performance for the following reasons:

  1. If you run a leisure battery to total discharge it would not be as effective.

  2. Amp hour ratings given to batteries are based on new batteries and in ideal conditions

We would never recommend totally discharging a battery ever, ideally you would never let it go below 50%.  

Calculating battery requirement

Caravan Equipment Wattage
Estimated hours you will use it without a re-charge Total watt hours e.g. Rating x hours
Three 8w lights 24w 10 hours 240 watt 
One 10w spotlight 10w 12 hours 120 watt 
Water pump 50w 30 mins 25 watts
Colour TV 50w 10 hours 500 watts

If you add up the total watts used e.g. 240 + 120 + 25 + 500 = 885 watts

To work out the total number of amp hours you divide by the voltage (12v) 885 watts /12 volts = 74 amp hours. 

Preserving the life of your battery

There are a number of ways to keep your battery working longer. 

  1. Switch off all appliances when they are not being used

  2. Avoid using high drain appliances such as televisions etc

  3. Keep your battery regularly topped up.

  4. Consider a battery charging device (see below)

A guide to caravan voltage meters

If your caravan has a volt meter fitted, if not a simple volt meter will suffice, you can check your batteries condition using the following guide.  Even though batteries are rates at 12v a fully charged battery will give out nearer 13v (see guide below)

Voltage shown on voltmeter Guestimate of battery condition
12.7v or higher Fully charged
12.5v   Three quarters charged
12.4v  Half charged
12.2v  A quarter charged
12v or lower Empty 

Charged caravan batteryBattery Charging

There are a number of devices on the market that will trickle charge your battery.  The most environmentally friendly versions are solar powered or wind powered.  Other alternatives are a generator or to use the power in your car battery.  Although be careful not to drain your car battery - so it is only really advisable to do this while the car is being driven. There are a number of solar panel kits available that can be used to either tricle charge or charge up a caravan battery.

Where possible it's advisable to keep your battery charged up. Many batteries like the one shown on the right have an indicator panel to show when the battery is charged. As you can see there is a green symbol in the window showing that this battery is in good condition.

Winter lay up

Our advice is to remove your battery from your caravan when you lay up your caravan.  Make sure you keep it charged over the winter to ensure it is in good condition next time you want it.

When removing your battery always disconnect the negative lead first (black) and then the positive lead.  Often there will be a red cap on the positive side and a black or blue can on the negative.Connecting your battery you should connect the positive terminal first and then negative.  Always switch everything off first to prevent sparks etc.

If you leave your caravan on a storage site over the winter and want to leave your battery in your caravan then a solar charger may be a good way to keep it topped up over the winter months.