EG4 batteries in Home Assistant, locally

Set-up

1. Install the Mosquitto broker add-on in Home Assistant if you do not have a broker yet.
2. In MoniWatt for EG4 settings, enter the broker address and credentials.
3. Save. Home Assistant creates one device per pack plus a bank device.

Entities

• Bank: sensor.eg4_monitor_bank_soc, …_bank_power, …_bank_energy_remaining
• Per pack: sensor.eg4_monitor_pack2_soc, …_pack2_current, …_pack2_temperature, …_pack2_cell_delta
• Per cell: sensor.eg4_monitor_pack2_cell_09_voltage
• Status: binary_sensor.eg4_monitor_pack2_alarm

Automations for off-grid and backup homes

• When the bank falls below 30% during an outage, turn off the pool pump and the second fridge.
• When the bank is above 90% and the sun is out, pre-cool the house or charge the EV.
• Alert if any pack runs 5 °C hotter than the others for more than an hour.
• Weekly report of energy cycled through the bank.

JSON API

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

{
  "bank": {"soc": 64, "power": -2310, "energy_kwh": 9.8},
  "packs": [
    {"addr": 1, "soc": 65, "current": -14.9, "temp": 27.1, "delta_mv": 9},
    {"addr": 2, "soc": 63, "current": -15.2, "temp": 28.4, "delta_mv": 14}
  ]
}

Perfect for Grafana through InfluxDB, Node-RED flows or a quick script that texts you the bank level.