Hi Carol not sure that is correct either ? main batts don't charge leisure. the alternator does that .So normally you start the engine alternator puts back into the starter battery ..a relay operates and leisure battery gets charged ( I suspect the problem ) switch your fridge to 12 v that triggers a relay which it sounds way you van is wired draws from the leisure battery. (can you work fridge 12v without the engine running ?) Normally you cant but some can the reason you cant is to stop the main batt going flat.Didn't realise there were different ones, duh! To charge the leisure battery from the main battery?
Sorry, I appear to be missing the type of Motorhome it is. Have you stated?