[MikeS100]

Thanks Father Ted. I've done a bit more research and apparently modern chargers output 13.8v which is enough to keep the battery charged but not enough to over charge it and they are, as you say, designed to stay on all the time if necessary. I'm not sure if the charger in a 1995 caravan would be 'modern or not but I'll take my multi meter down to it at the weekend and test the voltage.