Pylontech diagnostics, without a laptop or a serial cable
Diagnosing a Pylontech stack used to mean a USB-serial adapter, a terminal program and reading raw console dumps. PylonCheck does it permanently: it talks to the BMS through the CONSOLE port and turns the answers into clear values for every battery — and keeps them, so a problem can be traced back in time.
The service port every Pylontech has
Next to the CAN and RS485 sockets used by your inverter, every Pylontech master battery has a CONSOLE port (RS-232). It is the port Pylontech's own service tools use. PylonCheck plugs in there with the labelled cable from the box.
- Separate from the inverter link: the inverter keeps working exactly as before
- Reads the whole stack through the master battery — up to 16 modules
- Polls gently, one command at a time, so the console is never flooded
- Never sends a write command: diagnostics stay strictly read-only
Every value the BMS exposes, decoded
| Group | Values | Why it matters |
|---|---|---|
| Charge | SOC, voltage, current, power, charging / discharging / idle | The live picture, for the stack and for each battery |
| Health | State of Health (SOH), cycle count, remaining capacity | Ageing, and whether one module wears faster than the others |
| Cells | Each cell voltage, lowest, highest, spread (Δ mV) | The earliest sign of imbalance or of a weak cell |
| Temperatures | Cells and BMS / MOSFET, lowest and highest | Heat shortens battery life; cold limits charging |
| Status & alarms | BMS state, protection and warning flags | Why a battery stopped charging or disconnected |
| Identity | Number of modules, battery type (low / high voltage) | Confirms every module of the stack answers |
What Pylontech diagnostics reveal
The problems below are invisible in an inverter app that only shows a percentage. They are obvious once you see cells and history.
Cells drifting apart
The spread between the highest and lowest cell grows week after week. Most of the time the cause is simple: the battery never reaches a full charge, which is when the BMS balances. PylonCheck tells you so by email.
One weak module
In a stack of four, one module reaches its limits first: its SOH or its lowest cell falls away from the others. Seen battery by battery, it stands out.
Temperature problems
A module that runs hotter than its neighbours, or a garage that drops below the charging range in winter.
Protection events
Over-voltage, under-voltage, over-current or temperature protection flags, shown as soon as the BMS raises them — useful for your installer or a warranty claim.
Silent disconnections
A module that stops answering, or a box that loses power: the cloud notices the silence and emails you after 6 hours.
SOC that does not add up
Compare what the inverter shows with what each battery reports, and spot a stack that is not calibrated or not fully charged.
Diagnostics built into the local dashboard
Event log
Recent activity and a boot history that survives restarts: when the box started, lost WiFi, or stopped hearing the battery.
Raw console data
The battery's unparsed replies, for the curious and for support — no terminal program needed.
Network page
WiFi signal over time and a one-click gateway test, to tell a battery problem from a WiFi problem.
Why PylonCheck never writes to the BMS
Some tools let you change BMS parameters remotely. We chose not to. A Pylontech stores several kilowatt-hours; a wrong parameter, a firmware mismatch or an interrupted write can leave a module in protection or worse. PylonCheck reads everything and changes nothing.
- No risk of bricking a module from a phone
- No setting changed behind your installer's back
- Balance problems are explained, and the fix is where it belongs: the charge settings of your inverter
Questions
Do I need a computer to diagnose my Pylontech?
No. PylonCheck replaces the laptop, the USB-serial adapter and the terminal program. Everything appears in a browser, locally or in the cloud.
Which port do I use: CONSOLE, CAN or RS485?
CONSOLE. CAN and RS485 stay connected to your inverter. The CONSOLE port is the service port and is not used by the inverter.
Can I see each battery of my stack?
Yes, up to 16 batteries: SOC, voltage, SOH, cycles and state for each. Detailed per-cell voltages are available for the first four batteries of the stack; all other values work for all 16.
Does PylonCheck fix imbalanced cells?
It diagnoses them and tells you why they drift. It does not force a balance through the BMS: in most cases the durable fix is letting the battery reach a full charge regularly, which is an inverter setting.
Can I send the diagnostics to my installer?
Yes: export the history as CSV, or give them the private JSON link of your live data.
Your battery, from anywhere. For 39 €.
Cloud dashboard, history, alerts, Home Assistant and MQTT included. No subscription.