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.Unless connected to a mains electricity supply, the 12V equipment in a caravan or motorhome relies on a leisure battery. Leisure battery technology differs from standard car battery technology as it is optimised to handle the loads and patterns of use that are common in caravans and motorhomes.