Anyone running Fogstar Drift LiFePO4 in a cabin setup long-term?

Picked up two of the Fogstar Drift 100Ah 12V batteries back in spring and they've been sitting in my cabin doing daily solar cycles ever since. Victron MPPT handling charge, Cerbo GX keeping an eye on things. All seemed fine until recently I noticed the SoC readings drifting a bit between the two — one's consistently showing ~5% higher than the other at rest.

Both are on separate Victron SmartShunts so it's not a shared measurement issue. Wondering if one BMS is just being optimistic, or if I'm actually seeing genuine capacity drift after ~200 cycles. Neither battery is getting warm or throwing any alarms.

Has anyone done capacity tests on Drifts after extended use? Thinking of doing a full discharge on each to see what I'm actually getting vs the rated 100Ah. Also curious whether Fogstar's BMS allows any kind of balancing adjustment or if it's entirely passive and I just have to live with it.

CarolWatson | 847 posts

@XU_VanLife nice setup! I've had a single Drift 100Ah running in my Welsh hillside cabin since last autumn so coming up for about 9 months of proper daily cycling now. Victron kit here too, SmartSolar 100/30.

Honestly impressed with how consistent it's been through winter - even when ambient temps in the outbuilding dropped pretty low, the BMS handled it without complaint. I did programme a low-temperature charge cutoff on the MPPT just to be cautious mind you.

One thing worth mentioning - the built-in Bluetooth monitoring is handy but I've found it slightly optimistic on state-of-charge readings compared to what the Cerbo reports. Nothing dramatic, just worth being aware of if you're relying heavily on that figure. How's yours holding up capacity-wise after the summer cycles?

BoxerDream | 1,204 posts

Running two Drift 100Ah units in my Transit conversion for about 14 months now — similar daily cycle profile to what @XU_VanLife describes, though obviously mobile rather than static.

Worth monitoring your cell-level voltages through the Cerbo if you haven't already. I noticed around month eight that one of my packs had a cell drifting 20–30mV above the others by top of charge. Fogstar's built-in BMS sorted it via passive balancing, but it took several weeks of consistent full charges to fully resolve.

Key thing I'd flag for a cabin static installation: temperature variance. Floor-mounted batteries in an uninsulated space will see capacity drop noticeably below 5°C. If your cabin gets cold overnight between October and March, consider insulating the battery enclosure — makes a measurable difference to usable capacity versus rated spec.

TrevorRoberts75 | 43 posts

Useful thread — been considering these for my Scottish Borders setup. Currently running Renogy 200Ah AGMs which are frankly on their last legs after two winters.

Quick question for @XU_VanLife and @BoxerDream — how are the Drifts handling low temperature charging? I'm seeing -5°C or lower some mornings up here and I know LiFePO4 can be touchy below 0°C without a heated battery box or low-temp cutoff. Does the onboard BMS actually protect reliably in those conditions, or are you relying on the Victron MPPT to hold off charging until temps rise?

Also wondering whether two 100Ah units in parallel gave anyone BMS balancing headaches, or did they just play nicely together from the off?