Basen Green V3 Battery, BT works, BMS is active, No RS485 or display data.

Had a similar headache with a no-name LiFePO4 pack a while back. BT connecting fine but RS485 absolutely dead in the water. Turned out the protocol selector jumper inside was set wrong from the factory — they'd shipped it configured for CAN rather than RS485. One jumper move and suddenly Victron Cerbo could see it properly.

Worth checking if the Basen has any internal dip switches or jumpers. Manufacturers like this often ship batches with different configurations depending on which market they're targeting, and the UK ones sometimes get the short straw with mismatched defaults.

Also — what are you using to talk to it? Some of these BMS units are fussy about:

• Baud rate (9600 vs 115200 is a common gotcha)
• RS485 adapter type (cheap USB adapters can cause all sorts of grief)
• Which protocol variant — PACE BMS, JK, Seplos etc. all have slightly different implementations even when they claim "standard" RS485

The display issue alongside the comms failure makes me wonder if it's actually a power rail problem on the BMS board itself. BT runs off a different circuit than the display and RS485 comms on several BMS designs I've seen. Wouldn't be the first time a dodgy solder joint has caused exactly this symptom.

Have you tried a full BMS reset? Not just cycling the battery — actually holding the reset button properly if it has one.

Would be useful to know what BMS chip is inside. Anyone else running Basen V3 packs who's cracked one open? Curious whether these share internals with anything more familiar.

@SOC_Nerd that's a really useful lead actually — I'd never have thought to check a protocol selector jumper. Is that something that's accessible without fully opening the casing, or are we talking about voiding warranty territory?

I've got a Basen pack on order for my shepherd's hut build and I'm dreading this sort of thing. The BT-works-but-RS485-dead scenario seems to crop up quite a bit with these Chinese packs honestly.

Do you know if Basen use a standard jumper config, or is it completely undocumented? I'm wondering whether their support docs (if you can even find them in English) would specify the correct position for RS485 versus CAN or whatever else they offer. Has anyone managed to get a proper protocol wiring diagram out of Basen directly?

@CornishBoater with the Basen Green V3 specifically, worth also checking whether it's expecting Modbus RTU vs CAN vs their own proprietary nonsense — because apparently Basen couldn't decide either 😅

On my narrowboat setup I wasted a solid afternoon before realising the baud rate was set to 9600 when everything else expected 115200. Dead obvious in hindsight but RS485 gives you absolutely nothing useful when it's wrong — just silence.

Try a USB-to-RS485 adapter and run a quick Modbus scanner to see if anything responds at all before diving into the hardware. Termination resistors are another sneaky culprit if you've got a longer cable run.

@SOC_Nerd hit the nail on the head with the jumper, but I'll add a pedantic footnote from bitter experience with my shepherd's hut backup setup: even with the correct protocol selected, the RS485 wiring polarity will silently murder you.

A/B+ and B/A- labels are not standardised across manufacturers — Basen included. I had mine wired "correctly" according to the manual, got absolutely nothing, swapped the pair, and suddenly my Victron Cerbo was chatting away happily.

Also worth confirming: is your RS485 adapter properly terminated? Missing 120Ω termination resistors on longer cable runs cause exactly this kind of ghost-signal situation — BMS alive, display completely dead, everyone scratching their heads.

Check polarity, check termination, then worry about Modbus vs CAN. Work through it methodically and you'll get there.

@SOC_Nerd @CornishNomad — worth adding that on some of these Chinese packs the RS485 A/B lines are swapped relative to what you'd expect from the label. I spent an embarrassing amount of time with my garden office setup assuming my USB-RS485 adapter was faulty, when actually just swapping the A and B terminals at the battery end fixed it immediately. The pinout on the Basen documentation (if you can even find it) doesn't always match physical reality.

Also double-check your termination resistor situation — RS485 runs longer than a couple of metres without proper 120Ω termination at each end and you'll get nothing but garbage data or silence. Victron's RS485-to-USB adapter handles this better than the generic dongles from the usual suspects. Try a short test cable first before assuming it's a protocol or jumper issue.

Great points all round. One thing nobody's mentioned yet — double-check your baud rate settings. On the Basen Green V3 I've seen them ship with either 9600 or 19200 configured, and there's no obvious way to tell which without trial and error. If you're using a USB-RS485 adapter on a laptop to test, fire up a terminal (I use RealTerm) and just try both before assuming the hardware's dead.

Also worth confirming your termination resistor situation — if you've got a long cable run or multiple devices on the bus, missing or duplicate 120Ω termination can make comms look completely dead even when everything else is spot on.

@Finn1991 makes a solid point about A/B being swapped — that catches people out constantly. Swap those wires first, it's a 10 second fix.