Eco Worthy 12v 280ah metal case battery cell over volt issues

Has anyone else had persistent over-volt warnings with these cells, or is it specific to certain batches? I picked up a couple of 280ah units for my garden office build last spring and the BMS was throwing fits almost immediately after a full charge from my Victron MPPT.

Took a while to troubleshoot but I eventually found the absorption voltage on the charger was just slightly too aggressive for what the BMS was comfortable with. Dropping it from 14.6v down to 14.4v seemed to calm things down considerably, though I'm not entirely convinced I've solved the root problem or just masked it.

A few things I'm still not sure about:

• Are the metal case versions using a different BMS spec to the earlier plastic case ones?
• Is the cell balancing genuinely active or just passive? Because mine seem to drift apart under load more than I'd expect
• Has anyone bypassed the stock BMS entirely and fitted something like a Daly or JK BMS instead?

I've seen some chat on YouTube suggesting the over-volt cutoff threshold on these is set quite conservatively from the factory, which could explain the false triggers — but I'd rather hear from people who've actually used them rather than rely on that.

Also worth mentioning my setup pulls fairly hard in winter (running a small heat pump for the office), so I wonder if temperature is playing a role too. These cells were sat outside in a vented enclosure before I boxed them in properly.

Anyone with a similar setup managed to get them running cleanly long-term? Would be good to know whether it's worth persevering or cutting losses.

@SaltyGrafter the BMS on those Eco Worthy metal case units is notoriously twitchy around the high-voltage cutoff threshold. From what I've seen, the cells themselves are usually fine — it's the BMS calibration that's the problem. Mine was triggering over-volt protection at around 14.1v on a 12v nominal setup, which is completely unnecessary on LiFePO4.

Worth checking a few things:

• Charge voltage setting on your charger/inverter-charger — should be no higher than 14.4v absolute maximum, ideally 14.2v for longevity
• Balance lead connections — a loose balance wire gives the BMS false cell-level readings
• Batch variance — spring 2023 units seemed particularly prone to this

I'd also recommend logging with a Victron BMV or similar to capture exactly when the trips occur. Raw voltage data makes diagnosis considerably more straightforward than going on warning lights alone.

Had this exact situation with a batch I picked up for the van about two years back. Spent a miserable weekend convinced I'd bought lemons.

Turned out my Victron MPPT was pushing absorption voltage slightly high — 14.6v on a 12v system sounds fine on paper, but combined with any cell imbalance it was enough to trip the BMS repeatedly on one of the two batteries.

Worth checking:

• Actual absorption voltage at the battery terminals (not just what the charger claims)
• Whether both batteries are showing the fault or just one consistently

If it's always the same unit, you've likely got a weak cell dragging the pack out of balance. A proper top-balance of the cells individually before reassembly sorted mine. Tedious process but it worked.

The BMS on these isn't the worst I've seen, it's just unforgiving of imbalance.

Interesting thread — I'm about to pull the trigger on a similar setup for my garden office and this is giving me pause.

@SaltyGrafter are you charging via solar with a Victron MPPT, or something else? I'm wondering whether the over-volt events are happening at the tail end of absorption, or more randomly throughout the charge cycle. That might help narrow down whether it's genuinely a dodgy BMS threshold or a charging profile mismatch.

Also curious — did the cells actually balance properly during initial top balancing, or did you just connect and go? I've read that some of these budget metal case units ship with cells already quite mismatched, which could explain why one cell races ahead and trips the BMS before the rest are full.

Trying to work out whether Fogstar or similar might be a safer route for my build instead.

@HollyGazer don't let it put you off entirely, but do yourself a favour and budget for a half-decent BMS from the off — the stock one on those Eco Worthy units is basically decorative. I run Fogstar cells on my static caravan with a Victron SmartShunt keeping an eye on everything, and the difference in reliability is night and day; the Victron actually tells you what's going wrong rather than just throwing a tantrum and shutting off at 3am when your fridge is running. @SaltyGrafter you'll want to check whether your charge parameters are actually set correctly too — "over-volt" sometimes just means whoever configured it set the cutoff threshold at the default rather than something sane for LiFePO4.

@HollyGazer worth checking what charge voltage your charger is actually pushing out before assuming the cells are at fault. Had something similar in the van — turned out my MPPT was set to AGM profile and hammering them with 14.7v. Cells were fine, just badly configured kit.

Grab a decent multimeter and measure at the battery terminals during charge. If you're seeing anything above ~14.6v on a 12v LiFePO4 pack, that's your culprit right there.

Also worth noting — the metal case Eco Worthy units do seem a bit fussier than prismatic cells in my experience. Not necessarily bad, just less forgiving of sloppy settings.