I own a 2005 Thor Magellan 36Z motorhome. Until recently, while on shore power, both the house batteries and the chassis battery received a trickle charge. I have never had issues wirh the house batteries. The chassis battery has died several times. I disconnected it, charged it, and all was good for a month or so, then again it would not crank engine. During those occasions, I verified that 13.4 volts was being provided to chassis battery while on shore power. The last time the engine would not start, I heard relays clicking in the engine compartment. I disconnected the battery, charged it, reconnected, and all is good, except it is not receiving a charge. I checked all fuses. Any thoights on why I lost chassis battery charging?