24v Lifepo4 charger set to specific voltage

So I've been down this rabbit hole recently with my shepherd's hut setup and thought it worth sharing what I landed on.

Running a 24v Fogstar Drift 200Ah bank and spent ages trying to nail the right absorption and float voltages. The Victron docs say one thing, Fogstar's own BMS spec says another, and half the threads I found were American so everything needed translating across anyway.

What I settled on after a lot of back-and-forth with Fogstar's support:

• Absorption: 28.4v
• Float: 27.0v (some argue lower, even 26.8v)
• Tail current: 2% of capacity

The float voltage is where I see the most debate. Lots of people run 27.6v which essentially keeps the cells at a higher state of charge permanently — fine if you're drawing heavily, but I reckon it accelerates degradation if the system just sits there trickle-charging all summer whilst you're not actually using it.

My garden office system next door is on AGM still (I know, I know — it's on the list) and that comparison really highlights how fussy LiFePO4 voltage settings feel at first but how stable they are once you've got it dialled in.

Anyone else found their BMS spec conflicting with what the charger manufacturer recommends? Curious whether people are just trusting the BMS to handle the cutoff and setting charger voltages slightly conservatively as a belt-and-braces approach. That's sort of where I've landed but not entirely convinced I've got it right.

@VivaroNomad your post got cut off mid-sentence — guessing the site ate it.

That said, I'll preempt the obvious: with Fogstar Drift cells the charge voltage ceiling matters enormously. The spec sheet says 29.2V for a 24V bank (3.65V/cell × 8) but in practice I target 28.8V absorption on my Victron MultiPlus, which keeps cycle life respectable without pushing cells to the knee of the curve where degradation accelerates.

Float is the other thing people botch — anything above 27.2V float is unnecessary and slowly cooks your calendar life. I run 27.0V.

Worth noting: Fogstar's own documentation is a bit vague on this. Pull the actual cell datasheet (EVE or CATL depending on batch) rather than trusting the pack-level numbers blindly.

What charge source are you running — solar, hook-up, or both?

@VivaroNomad yeah looks like your post got chopped — gutted, was really looking forward to reading where you landed on this!

I'm in a similar position actually, running a 24v bank and constantly second-guessing my charge voltages. Few questions while we wait for the full post:

• Are you using a Victron charger or something else?
• Did you end up going with the Fogstar recommended figures or did you tweak from there?
• What's your reasoning for the specific upper voltage — longevity over capacity, or somewhere in between?

I've seen people suggest anywhere from 27.6v to 28.8v as the absorption target for 24v LiFePO4 and it genuinely varies so much between setups. Would love to know what worked for you in a real-world hut environment rather than just going off spec sheets.

Looks like it cut off for me too — would love to see the full post @VivaroNomad, especially the voltage settings you landed on.

Running a similar Fogstar Drift bank in my van (12v mind, not 24v) and spent a fair bit of time tweaking the absorption/float figures on my Victron. Ended up dropping float to 27.0v equivalent and haven't looked back — cells sit happier long-term.

Curious whether you went conservative on absorption voltage or kept it closer to the 29.2v mark. Some folk swear by 28.8v for longevity with Drift cells specifically.

Ah, the cruel irony — a post about getting your voltages exactly right, truncated mid-thought. The forum gods have a sense of humour.

@VivaroNomad I'm running a similar-ish setup on my Ducato (hence the name, not exactly cryptic), and the voltage question nearly finished me off. My Victron MultiPlus settings went through more revisions than a government energy policy.

While we wait for the full post to resurface, worth mentioning: absorption voltage is where most people go wrong with Fogstar Drift cells in my experience — manufacturers quote one thing, real-world longevity suggests something rather more conservative.

What charger are you running it through? That'll likely determine how flexible your settings actually are.

While we await @VivaraNoNomad's post to magically reconstitute itself, here's the short version the universe clearly didn't want you to read: for a 24V LiFePO4 bank, set absorption to 28.4V, float to 27.0V (or disable float entirely — the Fogstar Drift will thank you), and do not let your charger sit at absorption voltage indefinitely like it's a lead-acid from 1987.

My Victron MultiPlus handles this beautifully once you've wrestled the config out of VE.Configure — ESS assistants not required, just patience and a decent laptop that isn't also running Windows 98.