Problems with Victron multiplus

Been running a Victron Multiplus-II 24/3000 in my van conversion for about eight months now, and I've had a frustratingly similar experience to what others seem to be reporting after moving up from a 12V system.

The most baffling one: plug into a hookup point (typically a campsite or my mate's garage), and the unit just sits there with the float LED lit, doing absolutely nothing meaningful — even when the Fogstar 24V LiFePO4 bank is sitting at 23.1V. It knows the battery is low, but behaves as though it's already satisfied. No bulk, no absorption, just float.

A few things I've checked and ruled out:

• Battery protect relay — confirmed it's not cutting out early
• VE.Configure charge profile — absorption voltage set correctly at 28.4V
• Grid input current limit — set to 16A, well within the site supply

What sometimes fixes it is toggling the Multiplus off via the VictronConnect app, waiting 30 seconds, then back on. It then picks up properly and bulk charges as expected. Not ideal when you're on a campsite at 11pm.

My current suspicion is something to do with how the unit is detecting the AC input voltage on initial connection — possibly a UPS function setting causing it to be overly cautious. I've not ruled out a wiring issue on the AC input side either, though it all looks clean.

Has anyone else on a 24V Multiplus (not the 12V equivalent) seen this specific behaviour? Wondering whether it's firmware-related — I'm on v497, not yet updated to the latest.

Hey @PaulaFisher91, eight months in and issues starting to surface is pretty classic with van installations – vibration and temperature swings do funny things over time.

One thing I'd check straight away is your DC wiring connections at the Multiplus itself. I've seen loose terminals cause all manner of bizarre behaviour that looks like an inverter fault but isn't. Give everything a proper torque-check with the correct spec from the manual.

Also worth pulling the VE.Configure logs if you haven't already – the Multiplus records fault history and it'll tell you far more than guesswork will.

What firmware version are you running? There were some known issues with certain builds that Victron quietly patched. The VictronConnect app should show you this easily enough.

Can you describe the actual symptoms in more detail? That'll help narrow it down considerably.

Classic van gremlin — before you dive into Victron's settings rabbit hole, check your DC cable connections at both the battery and the Multiplus terminals, because vibration works those lugs loose over months and a dodgy connection will cause all sorts of phantom faults on a 24V system (voltage drop reads as a genuine fault).

Also worth connecting via VictronConnect or VE.Configure to pull the fault history — the Multiplus-II logs everything, so you'll see exactly what it thought was wrong rather than guessing.

If you're running Fogstar or similar lithium cells without a proper BMS-to-Victron communication setup (DVCC enabled), that's another classic culprit at the eight-month mark when cells start showing any imbalance.

@PaulaFisher91 what firmware version are you running on the Multiplus-II? I had something similar crop up on my static caravan setup after about six months and it turned out VictronConnect was showing me an outdated firmware that hadn't auto-updated properly. Worth checking through VRM if you've got it connected.

Also — what are your charge settings configured to? I've seen people come unstuck when they've migrated settings from an older Multiplus and the absorption voltage ends up slightly off for their battery chemistry. Are you running lithium or AGM?

@MarineGeoff makes a good point about connections generally — I'd add: are you using appropriately rated fusing right at the battery? I nearly lost mine because the ANL fuse holder had worked loose over a few months of movement.

What does the error code actually show when it trips?

@PaulaFisher91 what's the actual symptom? "Frustratingly similar experience" covers a lot of ground — are we talking random shutdowns, overload warnings, charging dropping out, or something else entirely?

I've got a Multiplus-II 24/3000 in my garden office (static install, so different stresses to a van) and it's been solid, but I've seen people chase their tails for weeks because they never clearly defined the fault first.

One thing worth checking that nobody's mentioned yet — have you verified your battery BMS is actually communicating correctly with the Multiplus? A dodgy DVCC setup can cause all sorts of phantom behaviour that looks like an inverter fault but isn't. What battery setup are you running?

Also, VRM portal logs are your friend here. If you're not logging data, start now — you'll never pin this down from memory alone.