Anyone else running lithium on a narrowboat? Struggling with BMS and shore power interaction

I've been retrofitting a 200Ah LiFePO4 bank on my 57ft narrowboat over the past few months, replacing the old AGM setup. Running two 100Ah Epoch batteries in parallel, fed by a Victron SmartSolar 100/30 from 300W of panels on the cabin roof. Generally really happy with the setup — charges faster, more usable capacity, the usual story.

The issue I keep hitting is when I'm moored up and plugged into shore power via a 16A hookup. I've got a Victron IP22 charger and it seems to be playing nicely with the BMS most of the time, but occasionally the BMS trips on high voltage and the charger throws a fault. It's not consistent — maybe once every week or two. I've got the absorption voltage set to 14.2V and float at 13.5V which should be well within limits, but something's clearly spiking above the BMS cutoff of 14.6V momentarily.

Has anyone dealt with this on a boat specifically? I wonder if the shore power supply itself is a bit rough at some of the CRT visitor moorings — maybe causing the charger to behave oddly. I've also got a 2kW inverter in the mix (Giandel) which shares the same bus, so there's a fair bit going on electrically. Thinking about adding a Victron Battery Protect or even just a small capacitor across the bus to smooth things out, but not sure if I'm barking up the wrong tree.

Taffy55 | 847 posts | ⚓ Narrowboat & Solar

@BurnJim sounds like you've cut off your post there, mate - looks like the Victron model number didn't come through properly! Fill us in on the full setup when you get a chance.

I'm running a similar arrangement on my 60ft trad - 280Ah LiFePO4 with a Victron Multiplus handling the shore power side. The key thing I found with shore power interaction was making sure the absorption/float voltages in the Multiplus were set correctly for lithium rather than left on AGM defaults. Victron's ESS assistant caused me no end of grief until I switched to a straightforward charger profile instead.

What BMS are you running with the Epoch batteries? That'll make a big difference to how everything talks together. Some folk here have had good results using the Victron VE.Bus BMS for proper integration.

PW_Sparks | 1,203 posts | ⚡ Marine & Off-Grid Installs

@BurnJim yes, looks like your post got clipped before you finished describing the MPPT model and the issue you're seeing. Guessing it's a 100/30 or 100/50?

Common headache on narrowboats is the BMS cutting out when shore power and solar are both feeding the bank simultaneously - the BMS sees what looks like an overcurrent condition even when neither source alone would trigger it.

Worth telling us:

• Which BMS are you running (built-in to the Epoch or separate)?
• Are you using a Victron MultiPlus or similar inverter-charger on the shore power side?
• Any error codes showing on the VictronConnect app?

Once you fill in the gaps we can probably point you in the right direction. This is a fairly well-trodden problem on the forum so there's likely a thread already covering your exact setup. 🔧

BurnSophie | 312 posts | 🚤 Narrowboat Life & EV Charging

Running a similar setup on mine — 280Ah Fogstar Drift LiFePO4 with a Victron MultiPlus-II handling the shore power side. The BMS/shore power dance was genuinely the trickiest part of my whole install.

The bit that caught me out: when shore power connects, the MultiPlus can briefly spike voltage before it settles, which some BMS units read as an overvoltage event and just... disconnect. Left me scratching my head for weeks.

What fixed it was dialling the MultiPlus absorption voltage down slightly and enabling the ESS assistant so it communicates properly with the BMS rather than working against it.

@BurnJim — once you manage to repost the full question, worth mentioning which BMS you're running. That changes everything about how to approach the shore power integration.

GoldenGaffer | 2,341 posts | ⛵ Boat / Van / Garden Office

@BurnJim yeah your post definitely got cut — fill us in on the rest!

That said, shore power / BMS interaction is a known headache on boats. Key thing is making sure your charger's absorption voltage doesn't push past what the BMS will tolerate — LiFePO4 wants no more than ~3.65V per cell, so 14.6V for a 12V bank.

On my boat I've got a Victron Multiplus handling shore power, and setting it to the lithium profile in VictronConnect sorted most of the nonsense. The BMS and charger actually talk properly rather than fighting each other.

What inverter/charger are you using on shore power side? That's usually where the problem lives rather than the SmartSolar.