Why check a Pylontech at all?
A Pylontech battery rarely fails suddenly. It drifts: one cell a little lower, one module a little warmer, a stack that never quite reaches full charge. None of this shows in an inverter app that displays a single percentage. A regular check catches it early, while the fix is still a setting and not a replacement.
The checklist
- Every module answers. The number of batteries reported matches the number installed. A missing module usually means a LINK cable or addressing issue.
- The stack reaches 100 % regularly. At least once every week or two. Without full charges, the BMS cannot balance the cells.
- Cell spread at rest is small. From a few mV to about 30 mV is typical; a steady rise over weeks deserves attention.
- Cell spread is stable over time. Compare this month with last month — the trend matters more than the number.
- SOH is similar across modules. A module clearly below the others is ageing faster.
- Cycle counts are similar. Modules installed together should count roughly the same cycles.
- Temperatures are similar and reasonable. No module consistently warmer; the room stays above freezing in winter.
- No repeating alarms. One protection flag during an unusual event is fine; the same flag again and again is not.
- Charge and discharge look normal. Current and power behave as expected for your solar production and consumption.
- History is kept. If something ever goes wrong, months of data are what your installer or warranty claim will need.
Doing it by hand vs. automatically
By hand, most of this checklist needs a laptop on the battery's CONSOLE port and a service program, and it only gives you a snapshot. PylonCheck sits on that port permanently: points 1 to 9 are on your cloud dashboard at a glance, and point 10 is automatic — three years of history, kept for you.
Two checks are even done for you by email: if the box goes silent for 6 hours, and if the cell spread widens beyond your pack's own normal (with the likely reason — usually point 2).
What good looks like
| Check | Healthy | Look closer |
|---|---|---|
| Full charge | 100 % every week or two | Never 100 % for weeks |
| Cell spread at rest | ≈ 5–30 mV, stable | Rising, or above ≈ 100 mV |
| SOH across modules | Within a few % | One module clearly lower |
| Temperature | Room temperature, even | One module warmer; near 0 °C |
| Alarms | None | Repeating flags |
Indicative values for low-voltage Pylontech LFP stacks. Follow Pylontech's documentation and your installer for your exact model.