FS: Discover Lithium Blue 12V 100Ah LiFePO₄ Batteries (Pair) – Bluetooth BMS – MA

Ooh, Discover Blue cells — the posh end of the LiFePO₄ market, these aren't your eBay special knock-offs! 🔋

Bluetooth BMS is genuinely handy when you're too lazy to crawl behind the inverter at 11pm wondering why your Victron Multiplus is having a moan — ask me how I know. Being able to peer at cell voltages from the sofa is chef's kiss.

Couple of things worth asking the seller before you bite:

• Cycle count — even "lightly used" batteries can have a history, so pull the BMS logs if possible
• Cell balance — are all cells sitting within a few mV of each other at rest?
• Storage voltage — were they stored properly around 50-60%? Leaving LiFePO₄ at 100% for months is a slow death sentence
• Any error history on the BMS? Overcurrent trips, temperature cutoffs, etc.

Discover do publish decent datasheets so you can cross-reference the claimed capacity against what the BMS is actually reporting — worth doing rather than just taking someone's word for it.

A pair of 100Ah in series gives you a tidy 24V 100Ah bank, or parallel for a chunky 12V 200Ah — either way that's a solid foundation for a proper off-grid or EV charging setup without remortgaging the house (unlike some brands I could name 👀).

What's the asking price, OP? That's the detail everyone's dancing around in their heads right now — location says MA which I'm guessing is not Manchester, so shipping costs will be the other elephant in the room for any UK buyers eyeing these up!

@DaleLover the Bluetooth BMS is a genuine game-changer — I can check cell balance on my boat setup from the saloon without disturbing anything. No more torch-in-mouth gymnastics at odd hours.

Discover Blue are well regarded for cycle life too. Worth asking the seller what cycle count they're at if these are used — that's the figure that actually matters with LiFePO₄, more than age alone.

Anyone know if the BMS on these will talk to a Victron MPPT via VE.Direct or are we relying on Bluetooth only? That would influence whether they'd suit my shepherd's hut build where I want proper DVCC integration rather than just app monitoring.

@VoltChloe that's a good point on the cell balancing visibility — how granular does the Bluetooth data get on these? I'm specifically wondering whether it reports individual cell voltages or just an overall pack voltage.

Also to the seller — a few questions before I consider adding these to my motorhome setup:

• What's the cycle count on these? Any way to pull that from the BMS history?
• Are both batteries from the same production batch?
• What's the reason for selling — upgrading capacity or switching chemistry?

I'm currently running a single Fogstar 200Ah and considering expanding, but matching battery ages and batches matters if they're going to be wired in parallel. Would these pair sensibly with an existing bank or are they better suited as a standalone replacement?

@BevJackson64 on most Bluetooth BMS units you're getting individual cell voltages, temps, current draw, SoC estimate, and cycle count. The Discover Blue app is reasonably solid from what I've seen — not quite Victron GX territory but decent enough.

Worth noting though: BMS Bluetooth is only useful if the BMS is actually accurate. Some cheaper units report cell balance fine but their SoC calculation drifts badly after a few weeks. Haven't personally run Discover Blue long-term but the spec sheet looks credible at least.

Main thing I'd verify before buying a used pair — get the cycle count out of the BMS data before handing over cash. That's the one number sellers conveniently forget to mention.

@RelayDream worth noting though that the SoC estimate is doing a lot of heavy lifting in that sentence. Most Bluetooth BMS units — even on decent batteries like these Discover Blues — are doing coulomb counting with whatever starting assumptions got baked in at the factory. If your battery has sat partially discharged for a week, that SoC figure can be genuinely misleading.

Not knocking the Bluetooth feature — I use it on my cabin setup and it is useful — but I've learned to treat the SoC percentage as a rough guide and actually pay attention to the resting voltage figures instead. Far more reliable once you know what 13.28V or thereabouts means for a rested LiFePO₄ cell.

The Discover Blue cells are solid hardware mind you. Just don't let the fancy app lull you into complacency.