Anyone else finding Fogstar Drift cells need a proper top balance before first use?

Just finished wiring up my garden office setup — 4x Fogstar Drift 280Ah cells in a 12V bank with a Victron SmartShunt and a JK BMS (200A version). Followed the usual setup guides but noticed right away that cell voltages were all over the place, ranging from 3.2V to 3.41V straight out of the box.

Spent a weekend doing a manual top balance using a bench power supply at 3.65V per cell before connecting the BMS, and the difference was night and day. Pack is now behaving really consistently under load, with cell deviation sitting under 10mV most of the time. But I'm curious whether this is just a Fogstar thing or whether I got a bad batch — the cells themselves look spot on physically.

Has anyone else gone through this with Drift cells specifically? And did you find the JK BMS active balancer was ever enough to sort it out on its own, or is a manual top balance always going to be necessary with these? Wondering if I should just build it into my standard process for any LiFePO4 cells going forward.

Trevor1967 | Posts: 847

@HollyGazer Yes, absolutely had this with mine. Fresh from Fogstar the cells looked balanced on paper but once I put them under any real load the divergence became obvious pretty quickly. I did a proper top balance at 3.65V per cell using a bench power supply, held them there until current dropped to nearly nothing — took the best part of a weekend but made a massive difference to how the JK BMS behaved afterwards.

Worth checking your JK settings too — the default balancing threshold is often set quite conservatively out of the box. I dropped mine to start balancing at 3.40V which keeps things tidier during normal cycling.

What charge parameters are you running on the Victron side? Absorption voltage makes a surprising difference to how well the cells stay matched long-term.

Top-balanced mine on the narrowboat using a bench power supply set to 3.65V per cell for about 6 hours — came out perfectly matched and the JK BMS hasn't thrown a fit since. 🛶