I have 450AH of AGM lead acid on my boat. I am looking to add a 310AH LiFePo4 battery to the house bank. I am mounting 450w of solar.
From my understanding, LiFePo4 will take a complete charge much faster than the AGM. To me it makes the most sense to connect the solar to the LiFePo4 using my Smart 100/50 solar charge controller; and then to put a a 12/12 30A DC-DC charger from the LiFePo4 to charge the AGM. This would keep the AGM at float charge most of the time and I can keep the LiFePo4 between 20-80% SoC. In this situation the AGM would still service the house loads. From my understanding the AGM can deal with heavier loads than my LiFePo4.
My question is: Is there a reason more people don't do this? Is this a bad idea?
Most info that I can find online has an alternator charging a lead acid bank and a DC-DC charger topping up a LiFePo4 bank which is used as the house battery.