2018 Thor Hurricane 29M
Boon docking, had battery power. ran generator to charge batteries. use store on. Batteries charged if at all. ran for hours. Ran RV, batteries charge up fine using RV alternator. Got home and next day, no battery power at all. use store on. Battery tests to 12.7 V. Plug into shore power, all works. Test at 100 amp breaker, no reading. Any ideas???