Is Fogstar Draft actually worth it over a proper LiFePO4 for a budget narrowboat build?

Been pricing up battery banks for my narrowboat and keep going back and forth on this. The Fogstar Draft cells are tempting at the price point — you're looking at roughly £280-ish for a 100Ah 12V compared to a proper Grade A LiFePO4 from somewhere like Enjoybot or SOK which are sitting closer to £350-400 landed from the UK warehouses.

The Draft cells are Grade B, obviously. Fogstar are upfront about that — minor cosmetic issues, capacity might be 95-98% of rated. For a static garden office I'd probably just go for it without a second thought, but a narrowboat is a different animal. You've got vibration, damp, and the bank could be sat in a 5°C engine bay over winter. Not exactly ideal conditions to find out your Grade B cells have a dud one in the pack.

My current setup on the boat is a Victron SmartShunt and a MultiPlus-II 12/3000, so the monitoring side is solid — I'd know pretty quickly if a cell started drifting. That does make me more comfortable with the risk than someone running no BMS telemetry at all.

Has anyone actually run Draft cells for a full boating season? Specifically curious whether the cell-to-cell variance causes headaches when you're balancing a 200Ah or 280Ah bank. The maths on the saving is real — we're talking £140-200 back in your pocket — just not sure it's worth the gamble in a marine environment.

@VictronMaster worth bearing in mind that Draft cells are lithium-ion chemistry, not LiFePO4 — so you're trading some cycle life and thermal stability for that lower price. On a narrowboat that's sitting in a engine bay getting warm in summer, that's not a trivial concern.

I run proper LiFePO4 (Fogstar Drift 280Ah cells) in my static caravan setup and the peace of mind is worth the premium honestly. For EV charging off-grid I need that cycle durability.

For a budget narrowboat build though — if you're doing your BMS properly and not pushing them hard, Draft can absolutely work. Just don't skimp on the BMS trying to save elsewhere. What's your expected daily cycle depth looking like?

What @VivaroDream said about the chemistry difference is the bit that stopped me going Draft for my boat. On a narrowboat you've got vibration, damp, and temperature swings that LiFePO4 handles much better — the stability margin matters more than on a static install.

My main concern would be the BMS situation too. Are you planning to build your own pack from Draft cells or is there a pre-built option now? On water I'd want something properly integrated rather than cobbled together on a budget.

Genuinely curious what the actual cycle life difference works out to in real-world narrowboat use — has anyone run Draft cells through a full season of liveaboard use?

Great points from @VivaroDream and @PaddyDixon already on the chemistry side. One thing I'd add specifically for narrowboat use is the thermal environment — engine bays and stern lockers can get genuinely warm in summer, and NMC chemistry (which is what Draft cells are) is noticeably more sensitive to elevated temperatures than LiFePO4, both for cycle life and safety margin. On a static installation at home I'd be less concerned, but on a boat where you've got less control over ambient temps and potentially less ventilation, that gap matters more. The savings look attractive upfront but if you're replacing cells significantly earlier you've lost the argument on cost pretty quickly. What's your rough usage profile — are you continuous liveaboard or weekend use? That'd change my thinking on whether the Draft makes sense here.

The narrowboat angle is the critical bit here that I don't think's been fully unpacked yet. You're dealing with a damp, potentially unventilated battery compartment — and NMC chemistry (which is what Draft uses) is genuinely more thermally sensitive than LiFePO4 if a cell goes wrong. On my shepherd's hut build I use Fogstar Draft and it's been excellent, but that's a static, well-ventilated install where I can check it regularly.

For a liveaboard narrowboat situation, the ongoing monitoring burden matters. LiFePO4 will tolerate a slightly neglected BMS or a dodgy cell balance far more forgivably. The cycle life difference also compounds differently on a boat — you're likely doing daily charge/discharge cycles year-round rather than seasonal use.

Worth doing the maths on total cost per cycle rather than upfront £/kWh. The Draft's headline price often looks worse once you factor realistic cycle count into it.

Great thread, and @Charlie1981's point about the damp environment is really important. One thing nobody's mentioned yet — consider your charging sources on a narrowboat. If you're relying heavily on a trad engine alternator, you'll often see uneven charge profiles that LiFePO4 handles far more gracefully than lithium-ion chemistries. Draft cells need tighter voltage management to stay healthy long-term, and a tired alternator putting out inconsistent voltage is exactly the scenario that ages them prematurely.

For a budget build I'd also factor in that a proper BMS for Draft cells to make them genuinely safe afloat isn't cheap — once you've priced that in properly, the gap between Draft and entry-level LiFePO4 narrows considerably. What alternator setup are you running @VictronMaster?

Really good shout from @HelenMoore and @Charlie1981 on the environment side of things. One thing I'd add to the budget conversation specifically — don't forget to factor in your BMS when comparing prices. The Draft cells will need a decent external BMS, and a proper one (Daly, JK, or similar) that's rated for the current you'll be pulling adds another £60-120 to the total. Some of the "proper" LiFePO4 batteries come with BMS included and already balanced. Once you run the full numbers including busbars, balance leads and a decent enclosure suitable for a damp boat environment, the price gap narrows considerably. Still potentially worth it if you're comfortable building packs, but make sure you're comparing like for like rather than just the cell price.

@RussMitchell75 raises something I learnt the hard way in my shepherd's hut build — budget cells punish you when the application is demanding. A narrowboat isn't a static shed install; you've got vibration from the engine, thermal swings between winter moorings and a stoked stove, plus that ever-present condensation.

I ran Fogstar Draft in my motorhome for a season. Perfectly decent cells, no complaints — but a motorhome sits dry and relatively still.

The question I'd honestly ask is: what's your BMS situation? Because a proper BMS on cheaper cells will outperform an inadequate BMS on premium cells every single time.