Right now I have wiring in place for three ways to charge my aux battery.
First, and permanently connected, is the alternator when engine is running.
The next two are wired right now so that only one can be connected at a
time: Solar charge controller (and solar panel) and an onboard 30 amp
'smart' charger.
Question:  What kind of problems, if any, would I encounter if all three
were connected to the battery at the same time?  Assuming that only one
would ever be running at any time, would I expect problems such as the solar
controller seeing the voltage from the 110v ac charger and causing damage?
Or the solar controller seeing the voltage from the alternator and having
problems?  Or any other combination that should be avoided?  Just to be
careful I'm now set up so that the solar and the 110v ac charger can't be
connected to the battery at the same time but the ideal system would be to
have them permanently wired in.