Well, I had the same issues in the past. Filling the batteries every couple of months worked fine on my previous coaches, non-all electric. Now with an all electric it does not work. The corision was unbelievable.
But, I'm having problems addressing your issue as you do not list your coach make, model, year, electrical type, etc. It would sure help you to get better input if at least you listed some info, if even in your profile.
AGM batteries remove the problem totally, but I can not suggest anything as I do not know what you are dealing with.
Peter