Eco Worthy 3000 Charge controller / inverter- E3 Fault - 12v LifePO charged to 24v & swelled. What caused it ?

Horrible situation and one that still makes me feel queasy reading about it. Lost a Fogstar 100Ah cell a few years back in the motorhome — not through overcharge, but the experience of finding a swollen battery is genuinely alarming.

The E3 fault on those Eco Worthy all-in-ones is typically a battery voltage detection error, and here's where I think the story gets interesting. Those combo units read voltage at the controller board itself, not directly at the battery terminals. If there's any resistance in the cabling — loose connection, undersized wire, poor crimp — the controller can see a falsely low voltage reading and just keep pushing.

So it's probably not that a 12v system was literally charged to 24v in the sense of someone selecting the wrong profile. More likely the controller lost its voltage reference, entered some kind of fault/protection mode that still allowed charge current through, and the BMS on the LiFePO4 either failed to catch it or was overwhelmed.

A few questions worth digging into:

• Was the battery's own BMS separate, or integrated?
• What cable gauge was used between controller and battery?
• Did the fault code appear before or after the swelling was noticed?

The Eco Worthy units aren't terrible for the price but they do lack the granular protections you get from separating out a proper Victron MPPT and a standalone inverter. The all-in-one convenience has a real cost when things go sideways.

Would genuinely love to hear what others have seen with E3 codes — whether this is a known recurring issue with that particular unit or just an unfortunate confluence of faults.

@MarineVicky gutting, really feel for you.

The E3 fault on those Eco Worthy units is typically a battery voltage mismatch alarm — so the controller knew something was wrong but clearly didn't shut down fast enough to protect the cell. That's the danger with cheaper all-in-one units, the protection logic isn't always as aggressive as it should be.

Worth checking whether the BMS in the Fogstar pack actually triggered or failed to disconnect — a swollen cell suggests the BMS either wasn't rated for the voltage spike or was wired incorrectly and bypassed.

On the narrowboat I've always kept the charge controller and inverter as separate Victron units for exactly this reason — if one misbehaves, you've got independent protection layers rather than one dodgy unit taking everything down.

Definitely don't reuse that cell.

@BirchTrevor hit the nail on the head — someone let a 12v Fogstar have a 24v system setting as a surprise gift and it did not enjoy the experience.

@MarineVicky absolutely gutting, and yeah that queasy feeling doesn't go away quickly does it.

Worth adding — LiFePO4 cells are actually remarkably tolerant compared to other lithium chemistries, but overcharge is genuinely the one thing they cannot forgive. The BMS should have caught it, which makes me wonder whether the Fogstar unit's BMS was undersized for the current being thrown at it, or perhaps the high-side disconnect was simply overwhelmed before it could react.

On the Eco Worthy units specifically — I'd always recommend manually verifying the battery voltage setting before connecting anything. These combo units are convenient but the UI is notoriously ambiguous between 12v and 24v profiles. I've seen people on narrowboat forums catch this just in time.

Going forward, a separate Victron BatteryProtect as a secondary hardware failsafe is worth every penny — it operates completely independently of the charge controller's own logic.

@Boycie makes a fair point about LiFePO4 chemistry being relatively forgiving until it isn't — and when it goes wrong at voltage levels that far exceed spec, it goes wrong dramatically.

One thing nobody's mentioned yet: those Eco Worthy combo units often have the voltage setting buried in a menu that's genuinely easy to accidentally toggle, especially if you're scrolling through during initial setup. I've seen it on similar all-in-one units where a single long-press commits a setting you didn't intend.

Worth flagging for anyone reading this later — always verify system voltage with a multimeter at the battery terminals before connecting anything, regardless of what the controller display claims. Takes 30 seconds and costs nothing.

@MarineVicky — do you know if the BMS in the Fogstar cell attempted to disconnect before it swelled, or did the BMS itself fail under the overcharge condition?

@CliveBaker is right that LiFePO4 is the safer chemistry — but "safer" doesn't mean "immune to catastrophic misconfiguration."

The E3 fault on Eco Worthy units is typically an overload or abnormal battery voltage flag. If someone's programmed a 24V system profile onto a 12V bank, the controller will happily push charge at that higher absorption target — your BMS may well have been overwhelmed before it could disconnect.

Key lesson I always bang on about: verify system voltage in firmware before connecting batteries, not after. I went through this exact paranoia commissioning my cabin setup — triple-checked the Victron SmartSolar profile before I'd let it anywhere near my Fogstar Drift cells.

Also worth asking — did the original setup have a properly rated BMS with high-voltage cutoff? A good BMS should be the last line of defence here, but it's only as good as its configuration.