How to limit shore charging to a specific SOC range (e.g. 20% → 60%)?

Been wrestling with this one on the motorhome lately and figured others here must have cracked it.

Running a Victron MultiPlus-II with a Fogstar Drift 200Ah and a Cerbo GX managing everything. Solar does most of the heavy lifting via a SmartSolar MPPT, but when I'm on a site hookup I want to use shore power carefully — ideally keeping the bank between about 20% and 60% rather than hammering it to 100% every night.

The reasons are fairly obvious — longevity, cycle count, the usual lithium gospel — but the implementation is where it gets fiddly.

From what I've gathered so far, you can set a charge current limit and absorption voltage in VictronConnect to effectively cap the top end, but getting it to stop at a specific SOC feels like it wants a Node-RED flow or some MQTT trickery through the Cerbo. The lower limit (not discharging below 20%) is straightforward enough via the BMS or ESS assistant.

What I haven't worked out cleanly:

• Whether the ESS "Keep batteries charged" vs "Optimised" modes actually help here without solar being the trigger
• Whether anyone's done this purely through scheduled charge settings on the GX without needing Node-RED

Feels like there should be a more elegant answer than writing custom automations just to tell a £1,500 inverter-charger to stop at 60%.

Anyone running a similar setup on a motorhome or cabin system managed to nail this? Particularly curious whether folk with a Venus OS Large install have used the Node-RED route and whether it's as stable as it sounds in theory.

@BayPete this is exactly what I do on the boat — Cerbo makes it fairly straightforward once you know where to look.

In VRM or the local GUI, go to:
Settings → ESS → Minimum SOC — sets your lower bound.

For the upper limit, set your MultiPlus-II charge current to zero via a scheduled charge profile, or use Node-RED on the Cerbo to trigger a relay/virtual switch when SOC hits 60%, effectively disconnecting shore power from the charger.

The cleaner approach: ESS mode with "Keep batteries charged" off, combined with a Node-RED automation watching com.victronenergy.battery SOC. When it crosses your ceiling, flip the MultiPlus to passthrough via MQTT.

Fogstar Drift BMS should report accurate SOC over — does yours have the Bluetooth module? Worth cross-referencing readings.

@BayPete done this exact thing on the narrowboat and it took me an embarrassing amount of head-scratching before it clicked.

The bit people miss is that ESS Assistant and Scheduled Charging behave quite differently — ESS gives you the persistent SOC floor/ceiling control you actually want, whereas Scheduled Charging is more "charge now, stop later."

Set your minimum SOC to 20% in ESS, then use the Grid Setpoint to stop the MultiPlus pulling from shore once you hit 60%. It's not immediately obvious but you're essentially telling the system to prefer grid at a certain threshold rather than hard-capping charge.

Worth noting — Fogstar Drift's BMS does its own top-end protection anyway, but I wouldn't rely on that as your primary limiter. Let Victron do the heavy lifting and treat the BMS as a backstop.

@BayPete worth being precise about which setting you're using — there's a difference between the minimum SOC in ESS (which controls when grid assist kicks in) and the scheduled charging limits. A lot of people conflate the two and end up confused.

For your use case I'd go scheduled charging in the Cerbo — set your window, tick "stop on SOC" at 60%, job done. The ESS minimum SOC handles the lower 20% floor.

One pedantic note: Fogstar Drift cells don't love sitting at high SOC for extended periods anyway, so 60% is a solid ceiling if it's plugged in long-term. I do similar on the shepherd's hut hookup — MultiPlus-II, Cerbo, same workflow.

VRM portal lets you verify it's actually respecting those limits too, which I'd strongly recommend checking before trusting it unsupervised.

Good timing on this thread — I went through exactly this dance last spring when I started using shore power more regularly for the EV charging setup on the boat.

The bit that caught me out initially: the MultiPlus-II won't just stop at your upper limit on its own — you need a Node-RED flow or a scheduled charge profile in VictronConnect to actively tell it to back off. The Cerbo's ESS settings get you the floor sorted, but the ceiling needs a bit more deliberate wrangling.

I ended up using a simple Node-RED automation watching the BMS SOC figure, then flipping the MultiPlus to charger only mode at 60% and back to inverter/charger below 25%. Been rock solid for months.

@CurrentAffairs is right to flag the ESS distinction — mixing those settings up caused me a very confused afternoon! 🛥️

@CurrentAffairs makes the crucial distinction — that ESS minimum SOC setting tripped me up for months on the shepherd's hut build before I properly understood it.

What finally clicked for me: Grid setpoint and minimum SOC work together but serve different purposes. The minimum SOC stops discharge, not charge ceiling.

For your upper limit, you want the scheduled charging feature in the Cerbo's ESS menu — set your charge window, tick "stop on SOC", dial in 60%. Fogstar Drift cells are solid but lithium longevity genuinely improves keeping them out of the top 20%.

One gotcha I found: if you've got DVCC enabled (you should have with that setup), double-check your charge current limit is flowing through correctly from the BMS, otherwise the Cerbo's SOC estimate can drift and your 60% ceiling ends up being optimistic.