After making sure the water level is correct, consider physically disconnecting the batteries from the coach. Leave them connected to each other. Fully charge the batteries with your portable charger. Wait a couple of hours and take a reading. The reading should be 12.6 VDC or more. Let them set for a week. Take a reading. The reading should be 12.6 VDC or higher. If the reading has dropped, the batteries may be at the end of their useful life.
If the VDC reading remains at 12.6 VDC or higher, there is a drain on the batteries coming from the coach. This will require a bit of detective work to determine 1st which circuit is the cause and 2nd which component, on that circuit, is guilty.
2005 Newmar KSDP 3910 + GMC ENVOY XUV 37K lbs Moving Down The Road
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