Originally Posted by Bkbrod714
After I had it jump started I let it run for about an hour. It was reading between 13.5 and14.4 while running. A house after turning it off it read 11.7 volts. That is still hooked up to the motorhome.
The alternator is working fine. It has the required capacity.
You have two 12 volt systems. There is the "house" or "coach" system, and there is the "chassis" or "engine" system. I am not sure which system you measured 11.7 volts on, but that battery bank is deeply discharged (well below 50% SoC.)
It takes 14 to 18 hours to fully recharge a lead acid battery. An abused battery can benefit from 24 hours to restore lost capacity.
The battery can be charged to 80% SoC in 4 hours of charging, depending on the charger and the battery.
After 4 hours of running the engine you should see 12.4 volts or more "static" on the chassis battery.
Some RV's charge the chassis battery while plugged into shore power or when running a generator. Apparently yours does not.
There may be a defective connection between the coach and chassis systems. It may be a relay. It may be an electronic device. The RV may have been built without cross charging capability. See owner's manual.
Charge the chassis battery for 18 hours using a standalone charger. Voltage while charging should rise to 13.6 volts. 14.4 is ok for 4 hours only.
Recheck static voltage after 3 or 4 hours of rest. Voltage should be 12.7 volts or more.
Check water level before charging to make sure plates are covered. Add enough water to cover plates. Do not over fill. Electrolyte will spit and spray during charging.
Check water level after charging to bring water up to "full" mark.