Victron multi2 won’t invert

Seen this crop up a few times and had something similar with my own Multi-II 48/3000. Worth methodically working through the likely culprits before assuming it's a hardware fault.

Most common causes I've come across:

• BMS communication issue — if you're running a Victron-compatible lithium pack (Fogstar Drift, EG4, etc.) over VE.Bus or VE.Can, the BMS can assert a DVCC charge/discharge flag that silently blocks inversion even when the green LED suggests it's ready. Check Venus OS on your GX device — look under Battery Monitor → Details for any active charge/discharge flags.
• Low cell voltage protection — even if overall pack voltage looks fine, a single weak cell tripping the BMS will prevent discharge. What's your cell-level monitoring showing?
• ESS assistant vs standalone invert mode — if you've loaded an ESS assistant previously and then tried to switch to standalone invert, they can conflict badly. A full VEConfigure wipe and reconfigure from scratch has sorted this for me before.
• DC voltage drop under load — seen cases where the Multi appears healthy at rest but the DC cabling has enough resistance that the moment it tries to pull serious current, voltage sags below the low-battery cutoff threshold. Worth checking your configured DC input low shut-down voltage in VEConfigure.

What BMS are you running, and are you on a GX device? Also — when you say "returned to default for lithium," did you use the lithium preset in VEConfigure or just hit reset? Those aren't the same thing and the preset sets some parameters the reset won't.

Anyone else had the ESS conflict issue cause this? Curious whether it's more widespread than

@ThistleTel good shout. I'd add — check your BMS comms cable first. Half the "my inverter is dead" panics I've seen on here turn out to be the Multi sitting there perfectly healthy, just waiting for the BMS to give it permission to exist.

Classic case of the inverter being more emotionally dependent than expected.

@ThistleTel @CotswoldNomad both solid points. One thing I'd add that catches people out — check your DC cable voltage drop under load. Had my Multi-II refusing to invert and it turned out the voltage at the inverter terminals was sagging below the low voltage cutoff even though the Fogstar cells were fine at the battery terminals. Undersized cable was the culprit.

Quick check: measure voltage directly at the Multi's DC input while attempting to invert. If it's reading noticeably lower than at the battery, your cabling or connections are the issue, not the inverter.

Also worth verifying the input voltage range settings in VictronConnect — easy to accidentally have these misconfigured after a firmware update.

Good points from @ThistleTel and @CaddyProject, but nobody's mentioned the VE.Bus address conflict yet — particularly relevant if you've recently swapped or added units.

Also worth checking: low battery cutoff thresholds in VEConfigure. I've seen setups where the DVCC system-wide low SoC limit is set aggressively (anything under 20% on a Fogstar Drift 100Ah will trigger it fast), and the Multi just quietly refuses to invert without throwing an obvious alarm. Looks completely dead on the face of it.

Pull up VictronConnect or Remote Console and check the 'Inverter' tab specifically — not just the system overview. The devil's in the detail with these units. Had exactly this on my narrowboat last winter, convinced myself the Multi-II had died. Took me two hours to find a misconfigured low-voltage disconnect threshold. Embarrassing doesn't cover it.

@Boycie25 good catch on the VE.Bus conflict — that one bites people hard.

One thing nobody's touched on yet: assistant switch / remote on-off terminal. The Multi-II has a two-pin remote connector on the back. If that's open circuit with no link plug fitted, some units will just sit there doing nothing — no alarm, no error, just silence. Had exactly this on my 48/3000 in the boat fit-out. Spent an embarrassing amount of time in VictronConnect before spotting it.

Also worth checking VEConfigure → Inverter tab — specifically whether "switch as inverter only" is ticked when it shouldn't be, or the output voltage limits are set wrong for your load.

If you're on a shared bank with a Victron Lynx Shunt or similar, confirm the battery capacity and Peukert settings aren't causing premature low-battery cutoff either.