Seplos / Mason rack mount battery with 200A V2 10E BMS wanted.

Running a couple of Seplos Mason 48V packs in my garden office setup and honestly they've been solid. The V2 10E BMS is decent once you get the comms sorted — took me a faff to get it talking properly to my Victron Cerbo but once it clicked it's been rock solid.

Anyone else noticed the 200A variant seems to disappear off UK suppliers randomly? Fogstar had stock a while back but seemed to dry up. I ended up going through a direct freight shipment which was a bit of a gamble but worked out fine on the duty side.

Few things worth flagging if you're hunting one down:

• Double-check the firmware version before you buy second-hand — some older units have quirks with cell balancing at top of charge
• The rack mount frames vary slightly between batches, worth confirming compatibility if you're mixing and matching
• Seplos Battery Monitor software is free but a bit clunky, worth downloading just for initial setup and cell checks

If anyone has a used 200A V2 unit they're looking to shift, drop a message. Ideally UK-based to keep postage sensible — these things aren't light. Open to a complete Mason kit too if the price is right.

Would be good to hear from others running these in a similar setup. Curious whether anyone's pushed them hard over winter — mine handled the cold reasonably well but I did add some basic insulation around the cabinet.

Hey @BerlingoSolar, good to hear the Mason packs are working well for you — they're a decent bit of kit for the price.

Just a heads up, I've got a spare V2 10E BMS sitting in my workshop that came out of a pack I reconfigured. Pretty sure it's fully functional, just bench tested it a few weeks back. Happy to let it go for a sensible price rather than it gathering dust.

Drop me a DM with what you're after spec-wise and we can sort something out. Might save you waiting on a shipment from Seplos direct, which as I'm sure you know can take a while to land in the UK.

@BerlingoSolar got a spare V2 10E BMS sitting in a box doing nothing — pulled it from a pack I reconfigured. Think it's the 200A variant but I'd want to double-check the label before committing.

Also have a partial Mason enclosure kicking about if that's any use to anyone.

Drop me a message if interested, happy to sort something reasonable rather than it gathering dust. Postage from Scotland so factor that in, or if anyone's nearby a collection works too.

Re: the comms faff — I ended up using a USB-RS485 dongle and the Seplos Monitor software just to verify everything was playing nicely before handing comms over to the Victron. Made life a lot easier than going in blind.

@ExSquaddie don't leave us hanging mid-sentence there, mate — did it fall off a shelf onto your keyboard? 👀

@ExSquaddie the suspense is killing me! Though knowing this forum, either the cat walked across the keyboard or the wifi dropped at the worst possible moment 😄

Worth noting for @BerlingoSolar — if you do go down the second-hand BMS route, make sure you get the firmware version confirmed before buying. The earlier V2 10E builds had a few quirks with cell balancing at lower SoC that were patched out later. Not a dealbreaker necessarily, but worth knowing what you're getting into. I had one from a similar situation and spent an afternoon scratching my head before realising it just needed a firmware update.

Also check the comms cable pinout — some of the earlier units shipped with slightly inconsistent documentation and it catches people out. Happy to share my wiring notes if that's useful.

@ExSquaddie my Victron system nearly blue-screened waiting for the end of that sentence.