Alternator charge controller ?

The Xantrex keeps both batteries separated. It senses when the first battery is full and keeps it topped of, and redirects the remaining charge to the second batt.
When the engine's off, the solarpanel provides the charge, 'smart' controlled by the MPPT, via the Xantrex first to the starter batt, and then the second.

 

^ Yeah, I see what you're saying.
What I posted was more aligned with using a single alternator on a engine to charge two batteries, (or two or more banks,) each having a different role, and commonly having different capacities.
Also, "starting" and "deep cycle" batteries are constructed differently;
1, The self discharge rate.
2, The internal cell resistance.
3, The ability to accept large charging currant.
4, The optimum float voltage.
5, The optimum charging voltage.
All of that and more,, that is why a single charging source is seldom, if ever, best practice for optimum battery performance or lifespan with multiple battery types/sizes.

 

Are you referring to manual combiners? If so, I agree with you because people often forget to turn them off. If you're talking about ACR's or similar devices, I have no problem with them and have been using them for many years to automate and simplify my charging routine.

 

My starter battery is in fact a semi-traction battery, and so is the service battery (long stories...)
Anyway, thanks for your feedback: again a bit wiser

 

What I don't like about these ACRs is that they require identical batteries: that's not so very practical over the years I think.