Not familiar with your rig [Alpine Forum] but most coaches have one of several ways to keep the coach chassis batteries charged: 1--solar cells on roof; 2--a stand-alone battery isolator for when the diesel is running; 3--an echo charger that "trickle" charges the chassis bats from the house bats when the house bats are being charged from the inverter [ie, via shore power while in storage or while parked; 4-- something called a "BIRD" system [not related to Alpines]; or 5--newer Alpines have a solenoid between bats, controlled by comm system [Vansco], that opens/closes based on a pre-determined logic in the Vansco. The Boost button on many coaches manually override the Vansco or other logic and ties the chassis and house bats together. If your rig is so configured, a bad solenoid would explain why your chassis bats dont charge while in storage nor why your boost button doesnt tie the bats together.
2003 40' MDTS
Garden Ridge, Texas