Why we added it
The dashboard already showed every value the BMS publishes: state of charge, every cell, temperatures, state of health, three years of history. The question we kept receiving was simpler: "So, is my battery OK?" Reading forty numbers to answer that is a job for an installer, not for an owner on a Sunday evening. The health check does that reading for you, every time the page loads, from the latest reading of the battery.
The Health check, line by line
We did not invent thresholds to call a battery "bad". Each check relies on figures Pylontech publishes (an operating range of 0 to 50 °C, a 30 mV target between cells), on the alert settings you chose yourself, or on a comparison between your own batteries. A gap in the data stays a gap: nothing is estimated to fill it.
| Check | Green | Amber (keep an eye on it) | Red |
|---|---|---|---|
| Communication | Every battery answers | Link to the battery lost, or no data for a while | |
| BMS alarms | No alarm | Alarm reported, with the battery named | |
| Temperature | Between 5 and 45 °C | Below 5 °C or above 45 °C, close to the 0–50 °C range | Above the alert threshold you set |
| Cell balance | Spread of 30 mV or less | More than 30 mV below 97 % charge | |
| State of health | Batteries close to each other | 10 points or more between two batteries | |
| Batteries together | Same charge within 10 % | More than 10 % charge gap | |
| Wi-Fi link | Good signal, 90 % of readings or more in 24 h | Weak signal, or fewer than 90 % of readings received |
Two details matter. First, a cell spread above 30 mV is shown as normal when the battery is at 97 % or more: that is exactly when the BMS balances, so the spread widens before it closes (the cell balancing guide explains why). Second, state of health is never judged against an absolute figure, because different BMS versions calculate it differently. What tells you something is one battery drifting away from the others; the SOC and SOH guide goes further.
Amber means "not urgent". The most common amber line in winter is temperature: a garage at 3 °C is not a fault, but it slows charging (see Pylontech in winter). The second most common is Wi-Fi: a battery whose readings arrive only 80 % of the time is fine, but the history will have holes.
Your battery's day
This card tells today's story in one sentence, for example: "Today your battery has stored 6.2 kWh and given 4.8 kWh back to the house. It reached 100 % at 13:40. Lowest point: 21 % at 07:10." Below it, a 24-hour ribbon shows the charge level, coloured by what the battery was doing: charging, powering the house or resting, with nights shaded. Hovering the ribbon reads the level at any moment.
Three tiles complete it:
- Autonomy at your pace: how long the energy currently stored would last, down to 10 %, at your average discharge over the last seven days. It is steadier than the live estimate at the current power (which a customer asked for and which is still there), because it does not jump when the kettle goes on. It appears once the battery has been seen discharging for at least three hours.
- Cycles today: the energy given back today divided by the capacity of your pack. Half a cycle a day is a quiet house; more than one is a battery working hard.
- Today's peaks: the strongest charge and the strongest discharge of the day, useful to see whether an inverter limit or a big appliance is reaching the battery.
When your battery works
This is a small map: seven rows for the last seven days, 24 columns for the hours, in the time zone set in your Pylon-Monitor. Each square is the average power for that hour: green when the battery fills up, orange when it powers the house, grey when it rests. Below the map, two facts are picked out: your strongest charging hour and the hour the battery works hardest for you.
It is the quickest way to spot a pattern you can act on. If the battery is full by early afternoon every day and works hardest at 19:00, running the dishwasher or the water heater at 14:00 instead uses solar energy that would otherwise go to the grid. If you use Home Assistant, that is exactly the kind of automation you can then build on the same data.
How to get it
- On your Pylon-Monitor, open Settings > Public JSON access, tick it and copy the access key.
- Sign in on your account at pylon-monitor.com with the e-mail of your order and link the device with that key.
- Open the online dashboard. The health check is the first card; the menu at the top jumps to each section.
It is free, with no subscription, and it works with every Pylon-Monitor. Turning Public JSON access off stops the publication immediately; the device itself keeps working locally as before. If you look after several installations, the fleet view runs the same checks on every site and puts the ones that need attention at the top.
What it does not do
The health check reads and explains; it does not change anything in the battery. When cell balance stays amber day after day, the next step is a long full charge, which our Force Balance session organises with your inverter and reports on cell by cell. When two batteries of a stack keep drifting apart, the multi-battery guide lists the usual causes, from cables to mixed firmware.
Frequently asked questions
- How do I know if my Pylontech battery is healthy?
- Look at alarms, temperatures, the voltage spread between cells and how each battery compares with the others. The Pylon-Monitor online dashboard does this automatically and shows each point in green, amber or red.
- What cell voltage difference is normal on a Pylontech?
- Pylontech aims for 30 mV or less between cells. A larger spread is normal near the top of charge (97 % and above), because that is when the BMS balances the cells.
- How long will my Pylontech battery last tonight?
- Divide the energy stored above 10 % by your usual discharge power. The dashboard's "Autonomy at your pace" tile does this with your average discharge over the last seven days.
- Is the Pylon-Monitor online dashboard free?
- Yes. It is optional, needs only a free account and the device's Public JSON access setting, and has no subscription.
- Why does the health check show amber when nothing is wrong?
- Amber means "worth a look, not urgent": typically a battery below 5 °C in winter, a weak Wi-Fi signal, or a cell spread above 30 mV outside the top of charge.
Get the health check, your battery's day and the hour-by-hour map for every Pylontech battery you own, with three years of history and no subscription.
Order now — €59 One-off purchase, €59 all in. No VAT, no subscription.