What a Pylontech check actually involves
"Check the battery" covers two very different jobs. One is the thirty-second look: is it charging, is it full, is anything flashing red. The other is the real check: is this battery ageing the way it should, and is there anything in its numbers that will become a problem in six months. Most people only ever do the first, because the second has always required a laptop, a cable and a free afternoon.
This is the checklist for the second one. Everything below can be read from a Pylontech battery without opening it, without disconnecting it, and without touching anything the manufacturer's warranty cares about.
The eight readings worth checking
| # | Reading | What you want to see |
|---|---|---|
| 1 | State of Charge (SOC) | Tracks your actual usage pattern. Unexplained drops with no matching load are the flag, not the value itself. |
| 2 | State of Health (SOH) | High and falling slowly. The trend matters; a single reading tells you almost nothing. |
| 3 | Pack voltage | Consistent with SOC and with the other modules in the stack. |
| 4 | Current | Matches what you'd expect from the inverter right now — charging when the sun's out, discharging in the evening. |
| 5 | Per-cell voltages | Tightly grouped. The spread between highest and lowest cell is the number that matters. |
| 6 | Cell imbalance trend | Small and stable over weeks. Slowly climbing is the earliest warning sign you get. |
| 7 | Temperatures | Within the manufacturer's stated range, and similar across modules. |
| 8 | Alarm flags & cycle count | No active alarms; cycle count roughly in line with the battery's age and your usage. |
What each of these means in depth — and the rough figures that count as normal — is covered in the diagnostics guide. The point of the table above is the checklist itself: these eight, in this order, and nothing else is urgent.
The quick check: LEDs on the front panel
Before any software, there's the free check. Every low-voltage Pylontech module (US2000, US3000, US5000 and relatives) carries a row of indicator LEDs on its front: a run indicator, an alarm indicator, and a set of SOC lights that show roughly how full the module is in steps.
This tells you two useful things in five seconds: the module is alive, and it isn't currently alarming. What it can't tell you is anything about health — a battery whose SOH has quietly dropped, or whose cells are drifting apart, shows exactly the same happy green lights as one in perfect condition. Exact LED patterns differ between models and firmware versions, so read them against your own module's manual rather than a generic table found online.
The real check: getting at the numbers
All eight readings live in the BMS, and there are three realistic ways to get them out. The viewer comparison goes through each in detail; in short:
- Laptop on the Console port. Pylontech's own Windows software (PYLON Console, sometimes shipped as BatteryView) plus an RJ45-to-serial adapter. Free, complete, and the reference method. Its limit is that it's a session, not a habit — no history, no alerts.
- Your inverter's screen or app. Convenient and already there, but it reads the CAN/RS485 link, which describes the whole stack as one virtual battery. Readings 5, 6 and 7 above simply aren't available over it, per module — this is a protocol limit, not a software one.
- A permanent reader on the Console port. A device that stays plugged in and serves the numbers continuously. This is the only one of the three that turns a check into a trend, which is what readings 2 and 6 actually require to be meaningful.
Checking a multi-battery stack
If you run more than one module, check them against each other, not just against the spec sheet. Modules in the same stack, same age, same duty cycle should report closely similar SOH, similar temperatures and similar cell spread. One module drifting away from its siblings is far more informative than any absolute number, and it's the single most useful thing a per-module reading gives you that a stack-level reading never can.
This is also the check the inverter cannot do for you: to it, sixteen batteries and one battery look identical.
How often should you check?
- LEDs: whenever you happen to walk past. Free.
- Full manual check: realistically once or twice a year, if you're doing it with a laptop. Be honest with yourself about whether that will actually happen.
- SOH and cell-spread trend: these only mean anything as a curve over months, so they want continuous logging rather than any checking schedule at all.
- Temperature and alarm flags: these want a threshold alert, not a check. By the time a scheduled check finds a temperature problem, the problem has been happening for a while.
That last pair is the honest argument for permanent monitoring over a diary reminder: the two things most worth catching are exactly the two things a periodic check catches worst. The monitoring guide makes that case in full.
When is a reading actually a problem?
Resist the urge to diagnose from one number. A single odd reading is usually a measurement artefact, a cold morning, or the battery doing something entirely normal you happened not to expect. What genuinely warrants attention is a pattern: cell spread that widens week over week, an SOH curve that bends downward faster than the rest of the stack, a temperature that reaches its threshold repeatedly rather than once, or an alarm flag that keeps returning after being cleared.
And when a pattern like that does show up, the right next step is an installer who knows your system — not a forum thread and not a dashboard. Monitoring's job is to hand you a clear, dated history of what happened; interpreting a genuinely borderline case is still a human judgement.
Pylon-Monitor runs this checklist for you continuously — all eight readings, per battery, logged for trends, with alarms on the two that can't wait for your next check.
Order now — €49 One-time purchase, €49 total — no VAT, no subscription.