Multiplus II 5000 on-grid charger off

Been wrestling with this one on my static caravan setup and wondering if anyone else has hit the same wall.

I've got a Multiplus II 5000 connected to grid on AC1-in, and I want it to pass through mains power to my loads without it simultaneously hammering my Fogstar lithium bank with charge. Essentially I want the inverter running normally, loads fed from grid, but the internal charger effectively paused — without touching the input current limit or messing with any other settings.

The use case is pretty specific: during peak rate hours I want grid passthrough only, then let my solar (via a Victron SmartSolar MPPT) do the battery work during the day. Having the Multiplus charger kicking in during peak tariff times is just burning money.

From what I can tell there are a few possible routes:

• ESS assistant with grid setpoint tweaked
• Scheduled charge windows in VictronConnect / Venus OS
• Toggling the charger via DVCC settings on a Cerbo GX

But I'm not 100% sure which approach actually fully disables the internal charger without side effects on the passthrough or inverter behaviour.

Anyone running a similar setup on a static or van conversion who's cracked this? Particularly interested if you've done it cleanly through Venus OS without needing Node-RED or anything complicated. Does the "charger only" / "inverter only" mode switch in VictronConnect actually help here, or does that kill the passthrough too?

Had this exact thing on my boat setup. You need to enable ESS or set it to External Control in VEConfigure — the "charger off" flag is usually coming from the grid code settings.

Check your grid code is set correctly for UK (G98/G99). Wrong grid code can trigger that behaviour automatically.

Also worth poking around in the Assistants tab — if you've got an older assistant loaded it can override the charger state without being obvious about it.

VRM portal shows the charger state in real time if you've got a GX device, makes it easier to see what's actually triggering it.

@JennyCole worth noting that even with ESS configured, you'll want to double-check your minimum SOC and grid setpoint values in the ESS assistant — these catch a lot of people out.

In VEConnect (or VEConfigure via MK3 adapter), look under ESS Assistant → Grid setpoint and set it to something like 50W. If the Multiplus thinks it needs to export or the SOC is above your threshold, it'll deliberately back off the charger.

Also confirm your AC input current limit isn't set too conservatively — I had mine throttled to 6A on my Vivaro build and wondered why charging felt anaemic. Bumped it to 16A and the difference was immediate.

If you're not seeing the charger tab at all in VEConfigure, your firmware may need updating first via VictronConnect before ESS options even appear.

Really interesting thread — I've been going through similar head-scratching on my van build, though obviously grid-tie adds a whole extra layer.

Quick question for @JennyCole — are you using a Cerbo GX or similar for comms? From what I've seen, the charger-off behaviour can sometimes come down to the GX device not having the right assistant loaded in VEConfigure rather than the ESS config itself.

Also wondering — what's your battery setup? I've noticed with Fogstar lithium cells that the BMS signals can sometimes confuse the Multiplus into thinking it needs to cut charging when it doesn't.

Has anyone actually walked through the full VEConfigure assistant stack for this specific scenario? Would love to see a screenshot of a working config — feels like the kind of thing that'd help loads of people in this forum.

Good thread — this mirrors exactly what I was trying to work out when I set up my garden office system.

One thing nobody's mentioned yet: have you checked whether AC1-in is actually being detected properly? On my Multiplus II, I had to verify the input current limit wasn't set to zero in VEConfigure — it silently prevents the charger from engaging even when the grid is present.

Worth pulling up your VRM dashboard if you've got a Cerbo GX connected — the AC input status will tell you immediately whether the unit even sees a valid grid connection before you go deeper into ESS settings.

@VivaroWanderer makes a fair point about grid setpoints, but I'd confirm the basic AC detection first. What does your CCGX or Cerbo show for AC1-in voltage and frequency?

Great thread @JennyCole — one thing worth checking that I haven't seen mentioned yet is whether you've got PowerAssist enabled or disabled in VEConfigure. If it's enabled and your grid setpoint is misconfigured, the Multiplus can get confused about whether it should be drawing from the grid at all, which sometimes manifests as the charger appearing to switch itself off unexpectedly.

Also double-check your AC input current limit — if it's set very low (or being overridden remotely via DVCC), the unit will throttle charging right back to prioritise passthrough loads first.

What firmware version are you running? There were some quirks in earlier builds around charger behaviour with ESS that got ironed out. Worth eliminating that before diving too deep into configuration rabbit holes.