running an LFP 8S bank parallel with an 24V AGM

[Boron]

Before all the naysayers jump in and say its dumb, there is a reason behind my application. You need to be familiar with deep cycle AGM use - in practice rather than just speculating on curve comparison. Looking at the end of charge level an LFB will rest around 26.4V and an AGM around 26.6V, but the load curve of an AGM will drop down to ca 20V under load (its a golf cart type mini EV). I draw ca 50A max. I thought at first to consider some schottky power barrier diodes but I wonder if this is too simplistic. BTW I would use a separate isolated charger for each bank. The idea is to use some current from the LFP to add to the AGM main supply, so extending the run time of the AGM and also provide a reserve supply. The LFP will have an UVP set at 24V so will cut off. So in effect the LFP will augment the initial run time, it can also partially recharge the AGM during resting periods (stop/start trip) so dumping some coulombs back in.
I can see a lot of overlap confusion and need to be sure I am not pushing large amounts into the AGM from the LFP (say 20A max)

I was hoping a member here may have done a rough trial of something like this. Setting up a full monitored operation will be a big job. I want to see if I am within say 90% success level first or is it fundamentally flawed.

Anyone been down this route - eg you may have paralleled up a lithium battery on your truck cos the AGM was weak? AFAIK an LFP is not suited for CCA duty starting (although in theory a Lion can but you have to go direct and bypass the BMS and only for a short burst and be prepared for the worst

 

[sunshine_eggo]

Not dumb. Been done a few times on here with some testing, but I can't find the thread.

Would fuse the AGM in the event of a cell short.

No need to charge separately. Just pick a voltage that works for both banks.

The AGM bank is essentially just a backup to the LFP. AGM will do very little and the LFP will be nearly depleted before the AGM starts picking up the load.