Seplos BMS in Home Assistant, no soldering

How it appears

Enter your MQTT broker in the box settings and save. Home Assistant receives a discovery message and creates a MoniWatt for Seplos device per pack, with sensors such as:

• sensor.seplos_monitor_pack1_soc, …_voltage, …_current, …_power
• sensor.seplos_monitor_pack1_cell_01_voltage to …_cell_16_voltage
• sensor.seplos_monitor_pack1_cell_delta (spread between highest and lowest cell)
• sensor.seplos_monitor_pack1_temperature_1 to …_4, plus ambient and MOSFET
• binary_sensor.seplos_monitor_pack1_balancing and …_alarm

Power and energy sensors carry the right device and state classes, so the Energy dashboard accepts them directly.

Automations worth having

• Notify when the cell delta exceeds 30 mV at the top of charge: your cue to let the pack sit at full for a balancing session.
• Lower the inverter charge current when the shed temperature drops near 5 °C.
• Run the heat pump water heater while the pack is above 90% and the sun still shines.
• Log each alarm with its time to a persistent notification.

A cell card for your dashboard

Sixteen sensors stack nicely in an apexcharts-card or a bar-card. Sort them by voltage and the weakest cell is always at the bottom.

JSON for everything else

GET http://moniwatt.local/api.json?key=YOUR_KEY

{
  "packs": [{
    "address": 1, "soc": 76, "voltage": 53.18, "current": 18.4,
    "cells": [3.322, 3.325, 3.319, 3.331, ...],
    "delta_mv": 12, "balancing": [false, false, false, true, ...],
    "temps": [19.0, 19.2, 18.8, 19.1], "alarms": []
  }]
}