RVPOZWER 12V Lithium Battery 100Ah $99 ,48V 100ah $432

Seen a few of these pop up on eBay and Amazon lately. The price point is tempting, no question — but I'd want to know a lot more before putting one anywhere near my setup.

A few things I'd be checking:

• Cell grade — are these Grade A or recycled/pulls? Marketing copy rarely tells you the truth here
• BMS quality — cheap cells I can sometimes live with, cheap BMS I cannot
• Cycle rating — 2000 cycles or 4000? Big difference in cost-per-cycle when you run the numbers
• UK warranty support — who do you actually call when something goes wrong?

For context, I've got Fogstar Drift batteries on my boat and paid more, but I know exactly what I've got and there's actual UK support if needed. That peace of mind has value.

That said, I don't want to dismiss these outright. Some unknown brands do turn out decent — especially if the cells inside are from a reputable manufacturer like CATL or EVE. Has anyone cracked one open and checked?

The 48V 100Ah at $432 is the more interesting proposition for a full off-grid system — that's roughly £340 at current rates. Compare that to a Fogstar or even Renogy equivalent and it's significantly cheaper.

Would love to hear from anyone who's actually stress-tested one. Charge/discharge curves, temperature performance, whether the rated capacity holds up under load — that's the real data.

Anyone running these in the UK yet?

@BatteryRay the pricing alone should set alarm bells ringing — a genuine 48V 100Ah LiFePO4 with a decent BMS, proper cell grading, and cycle life worth talking about simply cannot be produced and shipped profitably at $432. You're almost certainly looking at recycled/reclaimed cells dressed up in a new case, or cells that won't hit anywhere near rated capacity under real load.

Key things I'd want verified before touching one:

• Independent cell testing (not just the marketing sheet)
• BMS specs — continuous discharge rating, balancing current, low-temp cutoff
• UL/CE documentation that's actually traceable, not a printed sticker

For context, I spec'd Fogstar Drift cells for my garden office build and even buying wholesale the numbers don't stack up against what RVPOZWER are claiming. Sometimes the cheapest battery is the most expensive mistake.

@PennineVanLifer is right to flag the pricing, but let me add something concrete. I've pulled apart a few of these suspiciously cheap units for my emergency backup testing — the BMS is invariably the weak point. Marketing claims 100A continuous discharge, reality is a thermal-throttled 40A before it folds. The cell capacity is almost always overstated too; I've seen "100Ah" cells bench-testing at 68-72Ah under realistic load.

For the shepherd's hut build I did last year, I seriously considered similar budget units before settling on Fogstar Drift cells. The price difference felt painful upfront but the cycle life data and actual BMS protections (proper low-temp cutoff matters in the UK) justified it completely.

If RVPOZWER can't provide genuine MSDS documentation, IEC 62619 certification, or a verifiable BMS spec sheet — that's your answer right there.

@LesWood78 curious what you found inside — dodgy cells or the BMS that was the weak point?

Either way, avoid. I charge a 48V bank off solar to top up the EV overnight and I wouldn't touch anything I couldn't verify cell-level data on. Fogstar and EVE cells at least have proper datasheets you can cross-reference.

The £ vs $ thing is also worth flagging — these listings often show USD pricing to make it look cheaper than it is, then the actual GBP checkout price tells a different story. Plus import duties on top.

Stick to known quantities. A failed battery at that voltage isn't just an annoyance, it's a genuine hazard.

@LesWood78 @HarbourHermit — what I'd specifically want to know is whether those 48V units have proper cell-level balancing or just a passive top-balancer that'll let your pack drift into a mess within six months.

I run Victron kit on both the garden office and the boat, and the amount of grief I've had diagnosing second-hand mystery batteries is frankly exhausting. At least with those I knew what I was buying into.

The £/kWh calculation only works if the thing still holds its rated capacity after 200 cycles. Has anyone actually cycle-tested one of these with a proper load tester? Not just "it seems fine," but actual measured capacity figures?

Until someone produces real data I'd stick with Fogstar or even Renogy before I'd touch an unknown brand at that price point. The saving isn't a saving if you're replacing it in 18 months.