Charging AGM and Lithium Batteries at the Same Time?

Question:

I plan to install (4) LIFEPO lithium house batteries in my sail boat with AGM starting batteries. I have a Balmar alternator with external regulator for LIFEPO batteries. When using a Victron isolator to protect the alternator diodes how is the current distributed to each bank? Also, how will the different AGM be affected by the LIFEPO charging voltage being lower for the LIFEPO house bank? Is it a problem worth mitigating? - Ernie

Answer:

When charging a lithium house bank and AGM starter bank we recommend using a DC-DC charger between the two banks and connecting the alternator directly to the AGM starter. This way the alternator is protected if the lithium goes “offline” and can still re-charge both battery banks.