Anyone else had their Fogstar Drift cells arrive way out of balance?

Picked up four 280Ah LiFePO4 cells from Fogstar last month for my garden office build — cracking price, no complaints there. But when I cracked the box open and stuck the multimeter on them, two cells were sitting at 3.27V and the other two were down at 3.19V. Not catastrophic, but not ideal either before you even start top balancing.

Spent a good few hours with a bench power supply nudging them all up to 3.65V one at a time before wiring the pack together. Running a Daly 100A BMS on them for now (upgrading to a Victron Lynx Smart BMS setup down the line when the budget allows). First cycle looked clean enough — my Victron SmartShunt is reporting solid capacity and the cells are tracking within 0.02V of each other under load.

Just wondering if this is par for the course with Fogstar, or did I get a dodgy batch? Did anyone else go straight to top balancing before first use, or did you just bung them together and let the BMS sort it out over a few cycles?

JennyPalmer | 847 posts

@DefenderSolar totally normal with LiFePO4 cells shipped from storage, don't panic! Manufacturers often store them at around 50% SoC for transport safety, and they can drift quite a bit sitting in a warehouse for weeks or months.

Before you do anything else, top-balance them individually with a bench power supply at 3.65V per cell until the current drops right off — I'd suggest doing this before connecting your BMS for the first time. Takes patience but it's absolutely worth doing properly rather than rushing.

Fogstar's cells have generally had decent reviews on here for actual capacity matching once balanced. What BMS are you planning to run with them? That'll affect how you approach the initial balancing setup.

How far out were the readings when you measured them?

Robbo51 | 1,243 posts

@DefenderSolar worth knowing that Fogstar actually recommend doing a proper top-balance before first use regardless of how they arrive — it's in their documentation if you dig around. Stick them all in parallel at 3.65V and leave them overnight, they'll sort themselves out. I did exactly this with my 304Ah batch earlier this year and they came out within 2mV of each other by morning. Your BMS will thank you for it later too — saves it working overtime trying to chase drifting cells under load. What BMS are you pairing them with? Some of the cheaper units struggle if the initial balance is too far out on first charge.

CornishNomad | 412 posts

Done this dance with three different cell batches now — the ones sitting at 2.8V are just sulking after a long nap in a warehouse, not dead. Grab yourself a decent bench power supply (even a cheap one off Amazon does the job), set it to 3.65V per cell with a current limit, and let them top-balance overnight before you even think about wiring the BMS in. My Fogstar cells arrived similarly grumpy last spring for the narrowboat build and they're absolutely flying now. @JennyPalmer and @Robbo51 have got you covered on the why — just wanted to add that patience here genuinely pays dividends; rush the balancing and your BMS will spend its entire life fighting voltage drift instead of protecting you. 🔋

LDVProject | 673 posts

@DefenderSolar what voltage were the outliers sitting at? I had a similar situation with a batch of EVE cells — two were down around 2.9V while the others were at 3.2V. Ended up doing a slow top-balance over about 48 hours using a bench power supply set to 3.65V with the current dialled right back to maybe 2A. Came out spot on across all four.

One thing worth mentioning that hasn't been covered — before you start balancing, give each cell a quick capacity test individually if you can. Occasionally a cell that arrives low has actually degraded rather than just self-discharged, and you'd rather know that before you've built the whole pack. Probably fine, but worth ruling out early rather than chasing gremlins once it's all bolted together.

T6Project | 89 posts

@DefenderSolar had almost identical with my Fogstar batch back in spring — two cells sitting noticeably lower than the others straight out of the box. What sorted it for me was a slow top-balance using a bench power supply set to 3.65V per cell with the current wound right down to maybe 2A once they started climbing. Took a good 24 hours but they all converged nicely.

Worth checking your BMS settings too once you're balanced — are you running a Daly or something like a JK? I found my JK's balancing current alone wasn't enough to deal with that level of initial imbalance, it really needed manual intervention first before the BMS could keep up.