Swapped to lithium on my narrowboat - worth every penny or am I just lucky?

Coming at this from a van background rather than narrowboat, but the fundamentals are identical so worth chipping in.

Switched my leisure bank to Fogstar Drift 200Ah cells about 18 months ago and the difference versus the old AGM setup is genuinely night and day. The usable capacity alone justifies the cost — you're essentially doubling your effective storage without adding a single physical cell, just by accessing that lower SOC safely.

A few things I'd flag that are specific to your situation though:

• BMS compatibility with your alternator is critical. Narrowboats tend to run the engine regularly for propulsion anyway, so you're likely charging hard and often. Make sure you've got a proper DC-DC charger (Victron Orion-TR Smart is the obvious choice) between the alternator and the lithium bank, otherwise a BMS disconnect under load can damage the alternator.
• Temperature monitoring if you're overwintering afloat — lithium doesn't like charging below 0°C and a boat hull can get properly cold.
• What inverter/charger are you running? Some older combi units don't have lithium charge profiles and you'll be undercharging without realising.

Whether you're lucky partly depends on your installation quality. I've seen plenty of dodgy van builds where people bolt lithium in without properly addressing the charging sources and then wonder why the BMS trips constantly.

What capacity did you end up with, and are you running a proprietary system like Victron or a more DIY approach? Curious whether narrowboat loads differ much from van — I'd imagine inverter draw for the galley is considerably heavier.

@XO_Sparks curious where you landed with the BMS side of things — did you stick with whatever Fogstar recommend or go your own route?

On my van build I paired Fogstar cells with a Victron SmartShunt and a separate Daly BMS, which works well but I've seen a few people on here report comms issues when trying to get the Daly talking properly to Victron kit over Bluetooth.

The other thing worth flagging for narrowboat folk specifically — charge profile from the alternator matters a lot more than people realise. Running lithium straight off a traditional wet-cell-tuned alternator can cook it. A Victron Orion-Tr Smart DC-DC isolator is practically essential, same principle applies whether you're on a canal or a campsite.

18 months is a decent sample size though — any capacity degradation you can actually measure, or still looking essentially factory spec?

@XO_Sparks snap — been running Fogstar cells on my narrowboat for just over two years now and the difference versus the old AGMs is night and day.

@JubileeClipHero5 the BMS question is the real crux of it. I went with a Victron SmartShunt alongside a dedicated BMS rather than relying on the Fogstar's built-in protection alone — mainly because I'm also charging from a 7kW shore hookup when I'm moored and wanted proper oversight of charge cycles.

The Victron ecosystem ties everything together beautifully through the app. Watching state of charge in real time while the boat's sitting unattended genuinely changed how I think about the whole setup.

Two winters in, zero drama. The cells barely blinked during last January's cold snap either — which was the thing I was most nervous about on a boat versus a static install.

Running Fogstar Drift on my garden office and the BMS question is the one everyone wrestles with.

On a boat I'd go Victron Smart BMS over whatever ships with the cells — the DVCC integration with a Cerbo GX is genuinely worth it if you've got any Victron kit already. Handles the charge disconnect cleanly without the inverter throwing a fit.

@JubileeClipHero5 the big gotcha with narrowboat installs specifically is bilge temperature — lithium hates sitting at low SoC in the cold, and boat bilges get properly cold over winter. Worth setting a low-temp cutoff on whatever BMS you land on.

@Gazza25 two years is reassuring to hear — 18 months seems to be roughly where people either love it or start noticing cell imbalance creeping in if the BMS wasn't set up right from the start.

@CE_Builds bold of anyone to wrestle with BMS choices when the canal will happily make that decision for you the moment you take a corner too fast and everything slides off the shelf anyway — my Victron SmartShunt has survived things my dignity hasn't.