That would be first good guess but there may be some testing needed, too.
It may be the chassis battery has lost all charge as there are drains left connected, even when we turn the disconnect switches off!
Safety/ liability comes over making you happy! So safety items are left connected.
OR
It may be as simple as corroded/dirty cables or the way switches were left.
If there was a coach battery disconnect left turned off, that likely cuts the charge from the converter to charge the coach side. But not power to coach and whether there is any system to move some of that charge to the chassis battery is still an open question.
So some looking may help sort what happened.
One semi simple way to get more info one whether the cables are good may be worth a try.
I the chassis battery is down but the coach is good, one way to test the cables is to use a dash switch. It has various names like boost, aux, etc. ?
Ofte3n ignored, never used and forgotten but do a search from the driver's seat for something like that which you may have forgotten!
Idea is that you can push that switch to do a "jump start" without having a second car or getting out the cables.
If a weak chassis battery won't crank the engine or generator, try pushing the boost (or whatever name?) switch and see if that connects a good coach in to crank the engine!
If this makes things work, it normally says the cables are good but that first battery may be bad!
See if this fits for your RV? click this snip to see better!
Be aware that this does not mean the battery is now good and keep in mind that you may be selling the RV with a bad battery as letting them go totally flat is often prone to damage!
