Spent £340 on a budget LiFePO4 setup — was it actually worth it?

Right, so about eight months ago I took the plunge on a budget battery system for the shed after a particularly grim power cut that left us without anything useful for 14 hours. Went with a Fogstar Drift 100Ah (£189 at the time), a cheap Renogy 40A MPPT controller, and a second-hand Victron Phoenix 375W inverter I found on eBay for about £65. Total outlay was roughly £340 once I'd factored in cable and a basic BMS display.

Eight months in, I'll be honest — it's held up better than I expected. The Fogstar has taken daily cycles without complaint, sitting at about 80% depth of discharge most days through winter. No capacity drop I can measure, cells still balancing nicely. The Renogy controller is... fine. Does the job. Wouldn't call it inspiring but it hasn't let me down.

The bit I keep thinking about though: was the Victron second-hand gamble the smart move, or just lucky? The unit had clearly been used in a van build before me, unknown number of cycles, no warranty. It's worked perfectly but I sometimes wonder if that £65 saving was genuinely sensible or just rolling the dice.

Has anyone else mixed budget-new with second-hand-premium on a tight build? Curious whether the Fogstar-plus-used-Victron approach is actually a reliable strategy or whether I just got away with it this once.

SomersetBoater | 847 posts

@KevLee great write-up, and honestly that Fogstar Drift is a solid shout for the money — I've got one running on my narrowboat and it's been faultless for coming up on two years now. The BMS on those handles partial states of charge really well, which matters if you're not always topping up to 100%.

One thing worth checking after eight months — have you done a proper capacity test yet? Just run it down in a controlled way and see what you're actually getting versus rated capacity. Mine settled at about 94% which I was well chuffed with for a budget cell.

What inverter did you end up pairing it with? That's often where people lose efficiency on tighter budgets and it's worth knowing for others reading this thread.

TracyRobinson | 1,203 posts

@KevLee eight months of real-world use is exactly the kind of data we need on here rather than just unboxing videos, so cheers for sharing. One thing I'd add from my own experience with budget LiFePO4 — keep an eye on your BMS behaviour through winter. I noticed mine got a bit temperamental around charge acceptance once temperatures dropped below 5°C in the shed. Nothing catastrophic, just slower charging than expected. Worth sticking a cheap thermometer in there if you haven't already, and some basic insulation around the battery can make a surprising difference. Did you go with a dedicated charger or are you running solar into it directly?

@KevLee curious what your actual usable capacity looked like after eight months — are you still getting close to the rated capacity or have you noticed any degradation?

Also wondering how it handles the colder months. My van setup has a Victron BMV-712 monitoring a Fogstar cell and I've noticed the BMS gets a bit cautious once temps drop below about 5°C — charges slower, occasionally cuts out entirely on really cold mornings.

Did you factor in any low-temperature protection, or is the shed reasonably insulated? That's probably my biggest concern before I do something similar for my garden office build — it's essentially unheated overnight.

RussMartin | 412 posts

@KevLee good stuff, and @StuKnight raises exactly the right question. One thing worth adding — with LiFePO4 you really shouldn't see much degradation at eight months, but the figure that actually matters is what you're pulling at. If you're drawing decent current through a budget BMS, voltage sag can make your usable capacity feel lower than it is. Worth checking your actual resting voltage after a full charge versus what the spec sheet claims. Also curious which inverter you're running with it — some of the cheaper pure sine units have a fairly high idle draw that quietly nibbles away at your reserves overnight even with nothing else connected. Might account for any shortfall you're seeing.

GlenChild | 847 posts

@KevLee solid write-up, cheers. Eight months on a Fogstar is reassuring to hear — I've been eyeing their 12V 100Ah for a similar shed setup myself.

One thing nobody's mentioned yet: how are you finding it in the colder months? LiFePO4 handles low temps better than lithium-ion generally, but charging below about 5°C can still cause issues without a heated BMS. My shed drops pretty sharply in January and it's been my main hesitation before committing. Did you take any precautions or just let it run and hope for the best? Genuinely curious whether that's caused any headaches given we've had a reasonable cold snap this winter already.

Wez1961 | 1,204 posts

Eight months on Fogstar tracks with my experience — mine's been running the garden office for nearly two years now, no complaints.

One thing nobody's mentioned: ambient temperature will skew your usable capacity figures considerably. Shed installs in winter can see LiFePO4 drop noticeably if it's getting below 5°C in there. Worth checking if your BMS is cutting charge at low temps — most budget ones do, which is actually correct behaviour, not a fault.

@StuKnight — capacity fade on decent LiFePO4 at eight months should be minimal, maybe 1-2% at most if it's been treated reasonably. If @KevLee is seeing more than that, I'd look at charging voltage first before blaming the cells.

£340 all-in is decent for a shed setup tbh. People overspend chasing brand names when Fogstar does the job fine.