Coach Battery Charge Problem - Help?

[gztyp7]

We bought a 2009 Thor Fourwinds Class C motorhome about 60 days ago. We took it on a local trip to test things out. It was very hot and we ran the air the entire weekend. Sunday morning we woke and found the AC was off and we had limited power. We were able to get the slide in and got the vehicle home. Thing seemed ok. The coach has been in the drive way unplugged for several days while my husband has been installing a tv swing arm. While we were doing this yesterday we noticed the lights were dim. So I plugged the shoreline in to the house and the battery was allowed to charge overnight.

This morning, the battery was dead. Did not take a charge overnight. My husband pulled the battery out and has it on the charger in the garage now and it appears to be taking a charge. Do you have any idea what the problem might be? Could it be a fuse, since the AC may have overloaded something and popped a fuse? Where do we being to look.

They vehicle was owned by an older couple and in great condition with only 14K miles so it has not been used much at all. We are planning a trip to Yellowstone in September and need to get this repaired/corrected.

Any tips or advice would be greatly appreciated. I look forward to your reply.

[deandec]

First check that the battery disconnect switch is not in the disconnect mode. Since you had dim lights, it is probably in the right position.

With the battery in the coach and the shorepower plugged in, use your volt meter at the battery terminals to see if you are getting @13.5 to 14.2 volts of incoming power.

If so the the battery charger is working but the battery is not taking the charge.

If the voltage is not at least 12.5 DCv then the battery charger is not working.

Do you have an inverter in the Rig? Does it have a battery charger included in it? If so, there may be breakers on the Inverter box that have tripped and prevent the battery charger from functioning.

Many rigs have inline fuses between the house batteries and the Inverter/battery charger. Perhaps a fuse in the battery or inverter area common wire has failed? Check the positive cable from battery to inverter for an inline mounted fuse.

[Gary RVRoamer]

The battery charger in the RV probably has built-in protection against a shorted battery. If the batteries were very low, it is possible the charger thought they were shorted and shut itself off.

Check the water in the battery cells too - they won't take much charge is the water (electrolyte) is low.