Somewhat related to the topic title.....
I just installed this device yesterday on my Outlaw 29H. Apparently it is / was standard on Winnebagos but works on any motorhome where the shore power does not charge the chassis battery. It uses the house batteries and acts like a battery maintainer without using a 110V unit.
Ultra TRIK-L-START Starting Battery Charger/Maintainer
The install was very easy. I actually installed mine inside the cab on the same panel as the Emergency Start switch so I can easily see when it is is Maintaining or Charging the chassis battery.
I connected it across the emergency start relay and added this 15amp automatic reset circuit breaker per the recommendations when adding additional wire length.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Now when its sitting for large periods of time, the chassis battery will remained charged.