Connecting/charging low SOC lifepo4 battery and high SOC bank?

[jdz]

I'm probably just not wording this correctly, but here's my use case:

Existing 48v 200ah lifepo4 battery bank (2p16s fortune 100ah cells, overkill solar bms), charged with hydro and solar. We stay between 80-100% soc typically thanks to the hydro.

I want to add another 48v 100ah (16s) battery that will live in an electric golf cart. I want to connect this in parallel to the existing bank to recharge, however, how do I limit the inrush between the high SOC and low SOC batteries? I realize I could charge this with a "charger" but then I'm going DC-AC-DC which seems silly. There must be an elegant way to do this DC-DC, right?

 

[sunshine_eggo]

I want to add another 48v 100ah (16s) battery that will live in an electric golf cart. I want to connect this in parallel to the existing bank to recharge, however, how do I limit the inrush between the high SOC and low SOC batteries? I realize I could charge this with a "charger" but then I'm going DC-AC-DC which seems silly. There must be an elegant way to do this DC-DC, right?

Yep. You just mentioned it in the sentence before OR you can discharge the high battery down.

Get them within 0.1V of each other. Roughly speaking, for each 0.1V difference, you may see up to 100A between them. It will be momentary, but you don't want to trigger short-circuit protection or over-current protection.

 

[jdz]

I appreciate your reply -- but surely there has to be a way to do this short of burning off a few hundred amp hours in my bank before connecting them? I could manually switch my charging sources from one bank to the other battery but looking for a more streamlined solution if possible...