Flyfasteddie
Dec 22, 2014Explorer
Using house battery graduall discharges chassis battery?
My 89 Montara class C has one house battery and one chassis battery tied together by a continuous duty solenoid that is manually activated by a toggle switch. The solenoid was originally activated by turning the key to the "run" position, but I changed it. Both batteries reside in the engine compartment separated by about 6' of standard sized battery cable.
When dry camping (which is what we do most of the time) both batteries start fully charged and disconnected from each other by the solenoid. When running 12v items off the house battery the Trimetric shows a voltage drop consistent with the load being applied, and there is no corresponding voltage drop on the chassis battery.
However, the chassis battery will gradually drop in voltage a tenth of a volt at a time consistent with the actual state of charge of the house battery. In other words if both batteries start at 12.8v and I run the furnace (7a load) the chassis battery will show a voltage drop to say 12.5v while the chassis battery still shows 12.8v. But over time the chassis battery will drop to 12.7, 12.6, etc and when the furnace is turned off, and the house battery voltage stabilizes it will be .1v less than the chassis battery.
This behavior will do exactly the same thing in the opposite direction when I start the generator and charge the house battery. The voltage on the house battery will rise to 14.4v, but the chassis battery will stay where it was (say 12.3v). As the house battery charges the chassis battery will very gradually rise .1v at a time until it reaches full charge again.
Any ideas how this voltage is "leaking" into and out of the chassis battery? I can put a regular charger on each battery individually and the voltage rise will not show up on the other battery. Also if the two batteries are at different voltages and the house battery is not being charged or discharged the two batteries will maintain their separate voltages and not equalize to each other.
When dry camping (which is what we do most of the time) both batteries start fully charged and disconnected from each other by the solenoid. When running 12v items off the house battery the Trimetric shows a voltage drop consistent with the load being applied, and there is no corresponding voltage drop on the chassis battery.
However, the chassis battery will gradually drop in voltage a tenth of a volt at a time consistent with the actual state of charge of the house battery. In other words if both batteries start at 12.8v and I run the furnace (7a load) the chassis battery will show a voltage drop to say 12.5v while the chassis battery still shows 12.8v. But over time the chassis battery will drop to 12.7, 12.6, etc and when the furnace is turned off, and the house battery voltage stabilizes it will be .1v less than the chassis battery.
This behavior will do exactly the same thing in the opposite direction when I start the generator and charge the house battery. The voltage on the house battery will rise to 14.4v, but the chassis battery will stay where it was (say 12.3v). As the house battery charges the chassis battery will very gradually rise .1v at a time until it reaches full charge again.
Any ideas how this voltage is "leaking" into and out of the chassis battery? I can put a regular charger on each battery individually and the voltage rise will not show up on the other battery. Also if the two batteries are at different voltages and the house battery is not being charged or discharged the two batteries will maintain their separate voltages and not equalize to each other.