Originally Posted by srponies
Is this how most Coach/motorhomes are setup? Can you post a link to the component(s) needed.
Well a lot of RV manufacturers are still fitting 14.4V converter/chargers with lead/acid house batteries, so looking to them for inspiration can be problematic
They fit battery monitors that work from voltage too, so they will show a battery at 100% state-of-charge when it could be as low as 80%. One reason we like the Trimetric monitors is that they show the actual power consumed, and they are expensive because they are more than a simple voltmeter.
There are chargers that will do what you want, and my guess would be that the high-end motorhome builders use them.
This page might have a suitable unit, but hunt around because there are others:
DC powered battery to battery charger