Anyone else running lithium on a narrowboat? Sharing my setup and a few headaches

I've been living aboard a 57ft narrowboat for about two years now and recently made the jump from a knackered bank of AGM leisure batteries to a 200Ah LiFePO4 setup from Fogstar. Total game changer honestly — I'm running a 400W solar array on the roof (two 200W panels in series), a Victron MPPT 100/30, and a Victron BMV-712 to keep an eye on state of charge. Heating is a Webasto diesel unit so that's not pulling from the bank, but everything else — fridge, lighting, inverter for the odd laptop charge — is running off it.

The issue I keep bumping into is charging from the engine. I've got a 70A alternator on the Beta 43 but without a proper DC-DC charger in the loop, I was worried about hammering the alternator trying to fill lithium at bulk rates. Ended up fitting a Victron Orion-Tr Smart 12/12-30 isolated DC-DC, which limits the charge current and protects the alternator nicely. Seems to be working well, but I'm only getting about 30A into the bank while cruising, which on a grey January day is sometimes the only charging I'm getting.

Has anyone gone bigger with their DC-DC, maybe a 50A unit or running two Orions in parallel? Wondering if it's worth the upgrade or whether I'm overthinking it. Also curious whether anyone's had issues with BMS low-temp cutoffs on cold mornings — mine tripped once at about 3°C and left me without power until things warmed up a bit, which was a bit of a wake-up call.

@CraftyRanger not a narrowboat person myself — I'm running a similar Fogstar LiFePO4 bank in a shepherd's hut — but the crossover in headaches is remarkable.

The thing nobody warns you about is how a Victron BMS talking to your charger can get weirdly territorial. Mine kept throttling back the solar input at the worst possible moments until I dug into the DVCC settings properly.

Also worth checking: low-temperature cutoff. My hut sits in a frost pocket and I had one brutal January morning where the BMS just... went silent. Completely caught me off guard.

Two years on lead-acid before switching, and honestly the capacity headroom alone was worth every penny of the upgrade.

What alternator protection are you running? That's the one I'd lose sleep over on a boat — an unprotected alternator and a lithium bank is a proper horror story waiting to happen.

Great thread @CraftyRanger — I've got a comparable setup on a 62ft trad stern and the improvement over AGM is night and day, isn't it.

One thing worth mentioning for liveaboards specifically: keep an eye on how your BMS handles the temperature swings between cruising and mooring up overnight. Mine was occasionally tripping the low-temp cutoff during cold mornings last winter before I sorted the battery placement away from the hull sides.

Also worth checking whether your alternator has any lithium-compatible charging profiles — a lot of the older Beta and Isuzu units can cause headaches without a proper DC-DC charger inline. I've got a Victron Orion-Tr Smart between mine and it's been rock solid since.

What inverter/charger are you running? That'll affect how well you're getting the cells topped up from shore power at the marina.

Great thread @CraftyRanger — been on a 58ft cruiser stern for about three years now and made the lithium switch roughly 18 months ago, so I recognise everything you're describing.

One thing worth flagging that caught me out initially: LiFePO4 doesn't like sitting at 100% SOC for extended periods, especially over winter when you're not drawing much. I've got mine set to charge to around 90% as standard, only bumping to full if I know I've got a heavy day ahead. Seems to keep the cells happier long term.

Also worth checking your BMS low-temperature cutoff settings if you're moored somewhere that gets properly cold overnight — mine tripped out on a February morning and took me an embarrassingly long time to diagnose. Simple fix once you know, but a right pain at the time!

What solar setup are you running alongside it?

Really useful thread, cheers @CraftyRanger. I'm on a 60ft semi-trad and made the switch to LiFePO4 about 18 months ago — best decision I've made on the boat by a long stretch.

One thing I'd flag that nobody's mentioned yet: if you're doing a lot of winter cruising, keep an eye on your BMS low-temperature cutoff. I caught mine refusing to accept charge one particularly grim January morning when the battery compartment dropped below 5°C overnight. Ended up insulating the battery box with some foil-backed foam and it's been solid since. Dead simple fix but it had me scratching my head for a good couple of hours before I figured it out.

What solar/alternator setup are you running alongside the Fogstar bank, @CraftyRanger? Curious whether you've put a DC-DC charger in to protect the alternator.

Great to see so many liveaboards making the switch! I'm on a 54ft cruiser stern and went LiFePO4 about a year ago — one thing nobody mentioned yet is the importance of getting your alternator protection sorted before you do anything else. Lithium will absolutely hammer an unprotected alternator because it just keeps pulling maximum current with no internal resistance to ease off naturally like AGMs do. I cooked a perfectly good 70A Iskra before I wised up and fitted a Wakespeed WS500 regulator. Expensive lesson! @CraftyRanger what alternator protection are you running? Also worth checking your BMS low-temperature cutoff settings if you're mooring anywhere without shore power through winter — woke up one February morning to find mine had disabled charging overnight because the batteries dropped below 5°C. Caught me well off guard.

Really interesting thread — I'm not on a narrowboat but I do run a small sailing boat and a shepherd's hut on LiFePO4, so I've accumulated a fair few questions along the way!

One thing I'm curious about that nobody's touched on yet — how are you all handling battery heating in winter? I know LiFePO4 cells don't like charging below 0°C, and a narrowboat engine room can get pretty chilly when you're moored up and not running the engine for days at a time.

Do your Fogstar batteries have the built-in low-temperature charge cutoff, or are you relying on a Victron BMS or similar to handle that protection?

On the hut I've got a Victron SmartShunt keeping an eye on things but the boat setup is my next project and I'd love to know what's worked for you all before I commit to anything.

Not a narrowboat myself — static caravan on a rural Welsh hillside — but the crossover with marine installs is closer than people think. Both environments are damp, both have awkward cable runs, and both will punish a sloppy BMS connection eventually.

@CraftyRanger the one thing I'd flag that nobody's mentioned yet: temperature compensation on your charge sources. Canal environments get properly cold overnight in winter, and LiFePO4 does not want charging below 5°C. Worth double-checking your Victron (assuming you're running Victron?) has the low-temp cutoff configured correctly — it's buried in the settings but it matters.