Triple Battery Management

[PeeBee]

I think you might be better served with an approach on a caravan camper site, however the solution has a number of variables I guess. I had a setup with Wet cell starter and large AGM bank in the back. I tried Strling Power Systems - expensive, marine focused and ratshit techncal backup or sales support when things failed during warranty period. I moved to CTEK , there was a 2 component system, expensive for what it was, was reliable though, and handled the charge fine unlit an act of stupidity on my behalf blew it up. The different battery types were not an issue, and similarly the AGM in the car and in the caravan is simply a plug.
I now run an Optima AGN crank and lithium bank in the rear. I use Renogy for the lithium, with the feed coming off the Optima. The Alternator is upgraded from 130amp to 300amp. The most I have seen the alternator charging at is 190amps. The Renogy has a program that wont start charging the Lithium until the float voltage in the AGM is achieved, so no flat crank battery - from what I see the charge to the Lithium bank starts within 10 mins for first start of the day. I use Victron for the solar controller but the Renogy will do that as well, so I have redundancy. The Renogy units are the only ones I can find that can do a 2 x 60 amp charge in parallel - no one else makes one - there is a problem around two units fighting each other and they will blow up if you dont get the parallel capability if you need a chrge above 60amp.
The renogy chare rate is 60amp per unit, works well. The Renogy uniy was around $250 and their technical backup is great I have found. So I use the voltage regulator to do its job on the Optima, then the Renogy confirms when it will start bleeding off to the lithiums, which then causes the Alternator to lift to the initial 120amps charge - its pretty simple, dont forget your in-line fuses and mechanical protection of cables and do a volt drop chck to ensure you run the right size charge cables, DC low voltage is a nightmare. Hope this helps.

EDit the different battery types will be a problem if you try to charge each type at the same time, but if the set up is piggy backed off the starter, then the charge controller would look after the AGMs independently and the alternator the crank wet cell