Does your coach use an inverter/charger or converter for charging the batteries. Fair difference in cost if considering replacement. Starting point though is to dig out the Digital volt meter and compare voltages with and without charger.
Charging voltage should be 1.5 to 2 volts higher than battery voltage.
2006 Gulfstream Friendship G7, Cat C7 and Allison 6 spd
Honda VTX and Cruiser Lift on the back
Blue Ox Aladdin, Brake Buddy, 2019 Chevy Blazer RS toad