RE: Battery Charging
Sorry to be late to the thread, just back from a week being parked and
living on my solar panels.

To Neils question: Huh?  Why?  One aux battery, one starting battery.  Aux
could be two or a bunch, wired in parallel for desired capacity.  Hard wire
solar charger (and or 110v charger) to aux batteries/battery.  Plug in solar
when you can, plug into 110v ac shore power if available. Have a separator
or isolator between aux and starting battery so both charge from alternator
when engine is running.  Trying to monitor/switch between seperated aux
batteries just complicates things.  Maybe in marine or aviation applications
where critical systems have to stay alive there is a place for multiple aux
systems but for camping in our rigs?
BTW, my two 50 watt panels kept ice in the Norcold and even ran the laptop
all day when it was heavy clouds and rain last week.  When the Sun came back
out my aux was up to the float voltage of 13.3 v by noon each day.  I think
the new MPPT controller is making the setup even better.