Fallo Overload Multicon 24 5000 120

Been mulling this one over after seeing a similar discussion crop up elsewhere online, and it got me thinking about my own setup.

Had a spell last autumn where my Multiplus-II 24/5000 was throwing overload faults seemingly out of nowhere — no massive load spike I could identify, batteries looking healthy on the Victron display, everything appeared fine. Took me a good few evenings of head-scratching before I started suspecting the BMS communication rather than the inverter itself.

The thing is, when your BMS throttles charge/discharge limits and the Multiplus doesn't get that signal cleanly via the VE.Can or BMS assistant config, it can behave oddly under load. Mine turned out to be a dodgy RJ45 cable between the Fogstar Drift battery and the GX device — looked perfectly fine physically, but was causing intermittent dropouts.

A few things worth checking if you're seeing random overloads on a 24V system:

• Actual battery voltage under load — not just resting voltage
• Whether your BMS is cutting out momentarily and the inverter is seeing a sudden voltage collapse
• ESS or inverter assistant settings — particularly the DC input low shutdown thresholds
• Cable quality on your comms connections, not just the power runs

I'd also say: don't immediately blame the inverter. These units are generally solid. It's usually something upstream.

Anyone else had overload gremlins on a 24V Multiplus setup? Curious whether others found BMS comms to be the culprit or whether there were other causes I haven't considered. Would be good to build up a proper list of causes in this thread.

@HarbourKev that fault code usually points to a DC ripple issue or the batteries can't sustain the current demand under load. Had something similar at my cabin last winter — turned out my cell groups were imbalanced enough that the BMS was throttling output right when the inverter needed the grunt.

Worth checking:

• BMS logs if you've got access
• Voltage sag under load (stick a meter on the DC bus)
• Cable sizing between battery and inverter

My setup runs Fogstar Drift cells and it sorted itself once I did a proper top-balance. Victron's support docs on the 24/5000 overload codes are actually decent — ESS assistant settings can also trigger false overloads if misconfigured.

What BMS are you running?

@HarbourKev had something similar on my motorhome build last winter — turned out my Fogstar Drift cells were fine individually but the BMS was throttling output under sustained load, which the Multiplus read as an overload condition rather than a BMS cutback.

Worth checking your BMS continuous discharge rating vs what the 5000 can actually pull at 24V — that's roughly 200A peak which catches people out.

Have you got VictronConnect logging enabled? The DVCC settings can sometimes mask what's actually happening at the battery side. What BMS are you running?

Hey @HarbourKev, worth checking your battery interconnects and busbar connections before diving too deep into diagnostics. I had almost identical overload faults on my 24V system and it turned out one of my busbar bolts had worked loose over the summer — looked fine visually but was causing enough resistance to spike the voltage drop under load. The Multiplus-II is quite sensitive to that sort of thing. Also, what's your battery cable cross-section? Running anything under 70mm² on a 5000VA inverter at 24V is asking for trouble, especially with longer runs. @WonkyWelder and @MultiPlusGeek are both pointing in the right direction too. Grab a proper clamp meter and check your DC ripple whilst the inverter's under load if you can. What loads were running when the fault triggered?

@HarbourKev had this exact fault pop up on my boat setup last winter. What nobody's mentioned yet — check your DC cable lengths and whether they're properly matched between your batteries. Unequal resistance across parallel strings causes all sorts of grief under heavy load and can trigger that overload code even when individual cells look healthy on the BMS.

Also worth logging your DC voltage during the fault using Victron's VRM portal if you've got a Cerbo or similar GX device. The ripple will show up clearly in the data and you'll know pretty quickly whether it's a battery delivery problem or something in the Multiplus itself.

Mine turned out to be a slightly undersized DC cable run — swapped to proper 70mm² tinned marine cable and the fault disappeared completely.