House battery charging issue
We can normally run 4-5 days on the house batteries (two six-volt "golf cart" batteries in series, for 12 volts) on our 2006 Itasca Navion. We're just back from a week and a half trip (total mileage probably did not exceed 500), and encountered a problem. On the second to last stop, after three days, the battery indicator (this is just about house batteries; motor battery was fine) was showing that the batteries were flat. They turned out to be nearly flat, although they had enough grunt to bring the slide in when we left camp (thank goodness; I really don't need to learn how to bring it in manually any earlier than I must). We then drove about five hours to the next stop, at which point the battery indicator showed just 2/3 charge. The motor's alternator charges the house batteries when the van is running, and a drive of that distance should have had them fully charged. We were at the last stop only overnight, and used the battery as little as possible. After a two-and-a-half hour drive home, the battery continued showing 2/3 charge.
I also note that the electrolyte, which I always top up before a trip, is down. Normally, I've found one or two cells below full, to a minor degree, and fine at the end of the trip.
I'll be starting by pulling the batteries, manually charging them individually, and getting them tested. My hypothesis is that a cell fried on one of them, and the alternator, diligently trying to bring them up to full charge, was overcharging the battery combination, leading to evaporation of electrolyte.
If that's correct, should I replace both batteries, in case of damage to the good one?
I presume that the house battery charging current is controlled by a separate voltage regulator from the voltage regulator controlling charge for the motor battery (otherwise, one or the other could be getting overcharged at any given time). Should I be testing that charging circuit, and is this something a good automotive electrical shop can test, or will I need to make an appointment with an RV shop (and wait and wait - the good one in this area is booked out for months)?
I also note that the electrolyte, which I always top up before a trip, is down. Normally, I've found one or two cells below full, to a minor degree, and fine at the end of the trip.
I'll be starting by pulling the batteries, manually charging them individually, and getting them tested. My hypothesis is that a cell fried on one of them, and the alternator, diligently trying to bring them up to full charge, was overcharging the battery combination, leading to evaporation of electrolyte.
If that's correct, should I replace both batteries, in case of damage to the good one?
I presume that the house battery charging current is controlled by a separate voltage regulator from the voltage regulator controlling charge for the motor battery (otherwise, one or the other could be getting overcharged at any given time). Should I be testing that charging circuit, and is this something a good automotive electrical shop can test, or will I need to make an appointment with an RV shop (and wait and wait - the good one in this area is booked out for months)?
