bounty caravan wont charge

I was hoping some one could offer me some advise I have a bounty caravan which is quite old but in very good condition apart from it wont charge.I have bought a new battery thinking that was the problem at 1st but the van will not charge it when it runs out.Has any one had this problem before and was It worth fixing.My nearest van repairs is 20 miles away and charge £80 to look at it so didnt want to bother if it means a massive repair.Also no one seams to have ever heard of the bounty so I cant get prices on line