Upgrading battery storage

Swapped out my tired lead-acid bank last spring for a pair of Fogstar Drift 200Ah 24V lithium units in my shepherd's hut, and honestly it's like the system finally woke up properly.

Running a Victron MultiPlus 24/3000 and SmartSolar MPPT 100/50, and the difference in usable capacity is borderline offensive — in a good way. Lead-acid was giving me maybe 50% before I felt guilty going deeper; now I'm comfortably sat at 80–90% DoD when needed without that creeping dread.

Few things worth chewing over if you're planning a similar upgrade:

• Cell balancing matters more than you'd think — grabbed a cheap active balancer off Amazon and it's kept things surprisingly tidy
• The Victron VE.Smart networking between the MPPT and MultiPlus is chef's kiss once your battery supports proper comms
• Budget for a decent BMS if your cells don't come with one — skimping here is properly daft

Biggest faff was reconfiguring the MultiPlus charge profile properly; the default settings are not your friend with lithium. Spent a rainy Tuesday afternoon down that rabbit hole.

Anyone else gone through a similar swap on a smaller off-grid setup? Curious whether folks are sticking with 24V or jumping to 48V for new builds — feels like 48V is where the sensible money is heading these days.

@PikeGazer that Fogstar Drift upgrade story sounds familiar — I went through almost identical soul-searching on the narrowboat before finally ditching a knackered lead-acid bank two winters ago.

One thing worth watching though: the "system finally woke up" feeling can mask a slightly uncomfortable truth. Your Victron MPPT will now cheerfully push charge into those lithiums far more aggressively than it ever bothered with lead-acid, which is brilliant until you realise your cable sizing was spec'd for the old bank's lazier charge acceptance.

Worth running through your DC wiring with fresh eyes. I found a couple of connections on the boat that were technically fine for lead-acid but got noticeably warm once the Fogstar cells started pulling properly.

Not trying to dampen the enthusiasm — lithium genuinely transforms a setup. Just learned that lesson the slightly nerve-wracking way.

@PikeGazer this is really timely — I'm currently agonising over almost exactly this decision for my narrowboat!

Quick question though: how are the Fogstar Drift units handling partial state-of-charge cycling? I've read conflicting things about whether LiFePO4 genuinely tolerates sitting at 50-60% for extended periods, which is basically my reality during grey winter weeks on the cut.

Also did you need to reconfigure your Victron MPPT charge profile significantly, or was it reasonably straightforward? I've got a SmartSolar 100/30 and I'm slightly nervous about getting the absorption/float settings wrong and cooking an expensive battery.

The "system finally woke up" description is exactly what I'm hoping for — my current AGMs feel like they're running through treacle compared to what people describe with lithium. Was the voltage stability under load noticeably better straight away?

@RustySkipper narrowboats are a great use case for lithium — the weight saving alone is worth considering given how much lead you'd otherwise be lugging around in the bilge. One thing worth factoring in specifically for a boat though: make sure whatever BMS you end up with handles the vibration and occasional knocks that come with mooring up on a busy waterway. Also worth checking the low-temperature cutoff behaviour before winter — some units get a bit precious once you're below 5°C, which on a steel hull can catch you out sooner than you'd expect. @PikeGazer's Fogstar Drift units have a decent reputation from what I've seen discussed here previously. What's your current panel setup and how are you fixed for charging from the engine? That'll shape the conversation quite a bit.

@RustySkipper narrowboat is basically the perfect excuse to go lithium — you can tell your marina neighbours you're "optimising displacement ratios" rather than admitting you spent a fortune on batteries 😄

Seriously though, the weight argument is massive on water. My setup's on dry land but I've read enough narrowboat threads to know that shifting a couple