As I tried to explain in my long response earlier .... there is one other recommendation: Replace the solenoid that connects the engine's alternator to the house batteries to charge them. On a 2007 motorhome that solenoid can have corroded contacts such that whenever the motorhome's engine is running it's alternator is not charging the motorhome's batteries at all, or only very little.
The engine alternator is a powerful way to charge motorhome batteries ... but it's no good if the $15-$20 solenoid that connects it up to the motorhome batteries has worn out contacts after hours and hours of use.