Pack by pack
Each battery in the rack gets its own line: charge, current, temperature and health, so outliers stand out.
Pre-order · ships on 10 November 2026
Watch your EG4 battery bank like a pro installer would
EG4 batteries are built for big off-grid and backup systems. MoniWatt for EG4 shows what each pack in the rack is doing, live, without a laptop or a cloud portal.
- Colour screen + Wi-Fi dashboard
- No subscription
- 14-day returns, 2-year legal guarantee
< 0.5 Wpowered by USB-C
0settings written to your battery
€49.00screen and cables included
10 Novpre-orders ship
A rack of EG4 LifePower4 or EG4-LL batteries is a serious investment: several packs, often 15 to 30 kWh, running a whole house through outages or off the grid entirely. The inverter screen gives you one state of charge for the whole bank. It does not tell you that pack 3 runs warmer than the others, or that one cell in pack 2 hits the top first every afternoon.
MoniWatt for EG4 connects to the RS485 communication port of your batteries and reads each pack’s BMS directly. You get a screen at the rack, a dashboard on your phone over home Wi-Fi, and sensors in Home Assistant. It only reads, so it never fights your inverter for control of the batteries.
What you get
Cells you can trust
All 16 cell voltages per pack, with the spread in millivolts, to catch imbalance early.
Ready for outages
Know exactly how much energy is left before the grid comes back, from your phone, in the dark.
Alarms by e-mail
High temperature, low cell, protection tripped or box offline: you hear about it, wherever you are.
Home Assistant native
MQTT discovery builds the devices for you; a local JSON API feeds Node-RED, Grafana or your own scripts.
No cloud lock-in
Runs on your LAN. Remote access is optional and can be turned off for good.
Your bank through a full day
Morning: packs wake up and start charging as PV comes in. Afternoon: one pack reaches full before the others, the BMS balances, and the bank tapers. Evening: AC and cooking pull hard, and you see which pack delivers the most current. The dashboard draws all of it.
The optional history keeps three years of data, so you can compare this summer with last winter or prove to a warranty desk how a pack behaved.
Live dashboardLive
SOC82%
Power-416W
Cell Δ12mV
ChargeDischargeState of charge
Up and running in three steps
- PlugThe supplied cable goes into the RS485 / CAN port of your EG4 battery; USB-C into any phone charger.
- ConnectJoin the box’s Wi-Fi from your phone, pick your home network and set a password. No app to install.
- WatchOpen the dashboard in any browser, add it to Home Assistant, and set your alerts.
Made for EG4
| Models | LifePower4, EG4-LL, EG4 wall-mount |
|---|---|
| Connection | RS485 / CAN port, RJ45 cable included |
| Your existing wiring | Untouched — the box reads, it never writes |
| Network | Your home Wi-Fi (2.4 GHz) |
| Integrations | Home Assistant (MQTT auto-discovery), Jeedom, Node-RED, Domoticz |
| Power | USB-C, under 0.5 W |
Another EG4 model? Tell us when you order: your box is prepared and tested for it.
Your data, your way
The values the box reads can go into Home Assistant, where you build your own dashboards and automations. Here is what a reading looks like.
GET http://moniwatt.local/api.json
{
"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}
]
}
Shelf-sized, rack-friendly
One RJ45 socket goes to the batteries’ RS485 bus, one USB-C socket takes power from any charger. At the box sits on top of the rack or on the wall next to the inverter.
The design comes from Pylon-Monitor, a box already monitoring Pylontech batteries in homes across Europe. The EG4 edition adds an RS485 / CAN board and firmware written for the EG4 BMS.
Designed and assembled in France
Each box is prepared and tested in France before it ships, by the team that makes Pylon-Monitor for Pylontech owners.
Questions before buying? Write to [email protected]: a person answers.
MoniWatt for EG4
€49.00
VAT not applicable (art. 293 B CGI) · shipping calculated at checkout
- MoniWatt for EG4 with colour screen, RS485 / CAN interface
- RJ45 cable for the EG4 RS485 port
- USB-C cable (plug into any USB charger)
Ships on 10 November 2026 · free cancellation until dispatch
See every EG4 pack in your rack
Pre-order now. Tested on EG4 batteries before it ships on 10 November 2026.
Pre-order for €49.00Ships on 10 November 2026 · free cancellation until dispatch