Battery Question

If you have different voltages in the the chassis and house battery banks then the systems are not connected for some reason. Many older coaches did not have the BIRD (bidirectional relay with delay) or similar system. The way coaches without such a system is a very simple ignition relay that connects the battery banks together when the engine is running. Unfortunately if the coach is parked for too long the coach battery can go dead or drop low enough that the coach won’t start. Typically they do have an emergency start button on the dash but that doesn’t solve the underlying problem. As another poster mentioned they do sell products that charge the coach battery bank from the house converter if power is available. You can also retrofit modern version of a bird. Bottom line if the voltage is different then you either have a defective BIRD or one was never installed from the factory.