IDEA...charging house battery(set) underway.
It seems that the chassis alternator/VR system will often not fully charge the house battery(set) due to voltage drop between the two, or overcharge, boil the electrolyte away, for a deeply discharged...
Forum Discussion
landyacht318 wrote:
I've never slowly taken a battery to 10.5v, and I like BFL's hypothesis.
I wonder what the electrolyte level was before the 300 mile drive to the place where the batteries were takes to 10.5v. Was it the same set of batteries which twice had been"boiled nearly dry?"
Same batteries, still fully functional today. The first time it happened I only noticed because the time to charge depletion from 90% SOC was to short.
Any other heat sources nearby the battery?
No.
Don't more modern vehicles have some battery temp sensor on the chassis battery tray and adjust voltage accordingly? Perhaps this sensor is reading low.
Yes, many "smart" chargers use a temperature sensor in order to most rapidlycharge a battery absent overheating it. Our chassis VR's (discussion subject) are more DUMB than smart.
I've done many 4 hour drives returning from Baja with extremely depleted batteries without noticeable water loss, but they were wally world batts which almost never needed water, and I did not have an additional parallel alternator circuit to ekk out every last amp the alternator can muster, as I do now.
Perhaps you had a diode isolator, 0.5 volt drop minimum, or a less than robust isolator/house battery connection. In both of those cases the VR will only sense the chassis battery SOC.
