[folivier]

Don't really know yet. But I'm sure someone at the rally can help me figure out what happened.
We left the coach for a month plugged into 50amp. Inverter off, merge switch on, charger on. Checked my batteries today (8 wet cell 8d's) the 2 house batteries were ok and took no water. I have 2 8d's in one compartment connected by about 8' of heavy wire to the other 4 8d's in another compartment. The set of 2 8d's took a little bit of water, what I would expect after a month. The set of 4 8d's took about 3.5 GALLONS EACH! Yes, I put in 14 gallons total for 4 8d's! The top of each plate was exposed. Why would only 4 out of 6 batteries connected together boil the water out?
There was no amp draw on the batteries only a charge going in so hopefully they weren't damaged? I have them charging overnight.

After I first bought the coach I had to add 5 gallons of water for all 8 batteries. But they all took the same amount. The next 2 months I added just a little bit.

So everybody put on their thinking caps and help me figure this one out.