And anyway, unless the house and chassis battery choose to go dead at precisely the same time you can use one to “jump” the other. You probably even have a switch to connect the two for that purpose. That’ll let you start the coach engine from the house batteries or use the chassis battery to start the generator which you can then run until you get someplace for new batteries or repair. If all that fails you should have a lithium emergency pack in your kit. Cheap, small, powerful and very versatile. They also come in handy for emergency retraction of awnings and slides sometimes.