Made in France · read-only · Home Assistant ready

Your DIY Seplos pack, cell by cell, on your phone

You built the battery yourself: 16 cells, a Seplos BMS and a lot of care. Seplos Monitor lets you keep an eye on every one of those cells without opening a laptop.

Order now — €49.00 See what it shows →

€49 with cables. Dispatched from France; free cancellation until dispatch, 14-day returns.

Seplos Monitor box with colour screen showing pack state of charge, voltage and current

Anyone who has assembled a 48 V pack from 280 Ah or 314 Ah cells knows the feeling: the first weeks you check it every day. Is the balancing doing its job? Is cell 11 still lagging? Did the top charge actually reach the knee? The Seplos BMS knows all of this, but reading it usually means a USB adapter, a Windows tool and a cable across the garage.

Seplos Monitor stays plugged into the RS485 port of your BMS and keeps that data in view. The colour screen shows the essentials next to the pack; the web dashboard shows the sixteen cells, the temperatures and the balancing state from any phone at home; Home Assistant gets everything as sensors. It reads and never writes, so your BMS parameters stay exactly as you set them.

Sixteen cells in one glance

Bars for each cell, with the highest and lowest highlighted and the spread in millivolts.

Balancing you can see

Know when the balancer is active and on which cells, and watch the spread shrink after a full charge.

Four probes and the MOSFETs

Cell, ambient and power-stage temperatures, handy for a pack living in an unheated shed.

Protections spelled out

Cell over-voltage, under-voltage, over-current and temperature alarms, with an e-mail when one trips.

Made for Home Assistant

MQTT auto-discovery creates the cell sensors for you, plus a JSON API for Node-RED or ESPHome dashboards.

Local, read-only, quiet

No cloud needed, no setting written to the BMS, no polling storm on the bus.

The curve every DIY builder wants

A day on the dashboard tells the story of your pack: the morning charge, the plateau, the moment the first cell reaches the top and the balancer kicks in, then the evening discharge. When the cells drift apart, you see it on the spread curve weeks before it limits your usable capacity.

Switch on the optional history and you can compare this month with the one you commissioned the pack, which is the best proof that your build is healthy.

RS485 RJ45 socket and USB-C power input of the Seplos Monitor

RS485 in, Wi-Fi out

The Seplos edition of the box carries an RS485 interface behind its RJ45 socket. A standard network-style cable goes from the RS485 port of the BMS to the box; USB-C powers it from any charger. 70 × 70 × 36 mm, and it fits on the shelf above most rack cabinets.

It is the same box design that already monitors Pylontech batteries in homes across Europe, with a new communication board for RS485 and CAN and firmware written for the Seplos protocol.

Questions people ask first

Which Seplos BMS are supported?

We target the Seplos BMS V2 and V3 used in 16S 48 V packs, including the Mason-style DIY kits. Tell us your BMS version and board label when you order; we test that version before shipping, and if it cannot be supported you are refunded.

Does it replace the Seplos PC software?

For watching your pack, yes. For changing BMS parameters, no: the box is read-only on purpose, so you keep using the Seplos tool for configuration.

Can it read several packs?

That is the plan for paralleled packs on a shared RS485 line, each with its own address. Tell us your setup so we include it in testing.

All questions →

Give your Seplos pack a proper dashboard

Order now. Your box ships within ten weeks, tested on a Seplos BMS.

Order for €49.00Dispatched within 10 weeks · free cancellation until dispatch