Our battery in the RV went down this weekend and wouldn't stay up while running down the road. I checked it once back home, and with the switch in "Store", the battery puts out about 8.5 volts whet...
I think some may be in the weeds here. The STORE switch is to be used while the unit is in long term storage or non use for a time. Leave it in the USE position at all other times. In the STORE position battery is not getting charged from the engine or when plugged into ac. You may be replacing a good battery for nothing.