Battery Care

I bought a new Leisure battery for our caravan last year, on service this year i was told it was not performing to its optimum, although it is registering full charge on the gauge in the van. I was informed that i should invest in a charger for the van, would anyone out there have pointers as to what sort of charger is best, the van by the way is a Abbey Vogue 215 gts if this helps. thanks in advance