[ccjohnson]

We have 2 8D' for engine batteries and 2 8D's for house batteries. When plugged in to shore power, merge is always on as per Newell recommendation.
I check H2O levels every 4-6 weeks. I have one house battery that has been consistently taking 2-3 times more H2O than the other 3 batteries. All 6 cells are maintaining equal H2O levels in this battery. Any ideas?

[Richard]

That battery may have a bad cell. Use a hydrometer to,check each cell and see if one is weak. If it has a bad cell, it will generate more heat during the charge.. If it does have a bad cell, it's best to go ahead and replace. Eventually one bad battery will trick the charger into frying the rest of them and/or your alternator

[folivier]

Good explanation Richard. I think that's what happened to my batteries last summer. Left it for a month with the charger on and came back to find all 6 were very low on water. Ruined 3 of the 6. Not complaining too much though, forced me to get the Lithiums installed.
At Spearfish Chester had a load tester and we figured out that 3 were bad.

[Airplane Guy]

Guys,
What do you say about the caution on the house batteries "Do Not Add Water"?
....this will void warranty etc..

[Richard]

Bob, unless you have changed them, you have sealed AGM batteries. You couldn't add water without drilling a hole in the case. They do not vent, and theoretically cannot lose water.