It has to do with the remote you have. You need to have the ME-ARC (advanced) version of the remote control to get the custom user profile settings to be available.
I have the non-advanced version (the ME-RC 50) remote, so I just set mine to AGM2 profile for now (on my MS2812 inverter), to charge fine with my LFP 12v bank.
Reference:
View attachment 134748
Magnum sells a newer remote by p/n: ME-ARC50-L which is supposed to support a preset LFP battery profile, but rumor said it only works with the newer rev model inverters. So I opened a support ticket with Magnum and asked if I could use a ME-ARC50-L with my inverter, and he checked, he had to get my serial number of my MS2812 from me, later he indicated that I would have to also replace my main board too (since it was old rev board), to make that newer remote work (at my cost of course).
But I could still use an ME-ARC advanced remote if I wanted to be able to set custom user profile (which is the same as setting an LFP preset profile), so it doesn't really matter to me that there is a profile there called Lithium, since Custom User Profile can be set to same values anyways.
In my case, I just use the AGM2 profile on my ME-RC 50 remote, works just fine, since the absorption @14.5v and float @13.5v (with equalization effectively disabled, set same as absorption voltage) so I decided it's fine for LFP use.
In the case of 24v and 48v Magnum, looks like the AGM2 profile still looks fine for that. Based on Will Prowse's Sticky Thread I posted above (float is just a tad bit lower, but not a problem, might make it charge a bit slower on the last few percent (once it switches to float), but get more cycles and lifespan out of the bank):
12V 4S LiFePO4 Battery w/ BMS:
- Absorption: 14.5V
- Float: 13.6V
- Inverter Cut-off: 10.7V-12V (depending on size of load and voltage drop etc)
24V 8S LiFePO4 Battery w/ BMS
- Absorption: 29V
- Float: 27.2V
- Inverter Cut-off: 21.4V-24V
48V 16S LiFePO4 Battery w/ BMS
- Absorption: 58V
- Float: 54.4V
- Inverter Cut-off: 42.8V-48V