Short answer: a well-installed Pylontech US battery (LFP chemistry) can reasonably be expected to last well over ten years in a home. Pylontech’s datasheets quote several thousand cycles (over 6,000 on recent US models), and the warranty is 7 years, 10 when the battery is registered, with at least 70 % of the rated energy during the warranty. What shortens that life is mostly heat, long periods at full or empty charge, and cells left out of balance. The way to know how yours is ageing is to watch its State of Health, battery by battery.
What the numbers really mean
Cycles
One cycle is one full charge and discharge, which can be spread over several days. A home battery typically does around one cycle per day in summer and less in winter, so roughly 250 to 350 cycles a year. Even at the high end, several thousand cycles represent well over ten years. In most homes, calendar ageing (time and temperature) matters as much as cycling.
The warranty
Pylontech’s warranty for the US range covers 7 years, extended to 10 when the battery is registered, and guarantees at least 70 % of the rated energy during the warranty period (and not less than 60 % at the end of the extension). That tells you what Pylontech considers normal ageing: a slow, steady loss of capacity, not a cliff.
State of Health (SOH)
The battery management system (BMS) estimates how much capacity each module still has compared with new. It is shown as a percentage. It is the single most useful number for following the life of a battery, and it is not shown by most inverter apps.
The five things that age an LFP battery
- Heat. The biggest factor. A battery that lives in a hot attic or a sun-facing garage ages faster than one in a cool cellar. Aim for a ventilated, shaded spot, ideally around 15 to 25 °C.
- Charging in the cold. Lithium cells must not be charged below freezing. The BMS protects the battery by limiting or refusing charge at low temperature (the US datasheets give a charge range of roughly 0 to 50 °C, discharge roughly −10 to 50 °C; check your model). An unheated outbuilding in winter means less usable battery, and repeated borderline charging is not good for it.
- Long periods at 100 %. Sitting full for weeks (for example a backup battery that is never used) ages LFP cells slightly faster than sitting at a middle state of charge.
- Long periods near 0 %. Deep discharge followed by days without sun is the opposite risk. If the battery stays empty too long, cells can fall below the safe voltage and the BMS may shut the module down.
- Cell imbalance. The 15 cells of a module should stay within a few millivolts of each other. If one cell drifts, it hits the high or low limit first, the BMS stops charging or discharging early, and the usable capacity shrinks even though the other cells are fine. See our cell imbalance guide.
What matters less than people think
- Using the battery every day. LFP is made for daily cycling. A battery you use is not “wearing out” in a worrying way; that is its job.
- Partial cycles. Charging from 40 % to 80 % is perfectly fine; LFP does not have the “memory effect” of old nickel batteries.
- Charging to 100 % from time to time. A regular full charge actually helps the BMS recalibrate the state of charge and lets cells balance at the top.
Practical rules for a long life
| Do | Avoid |
|---|---|
| Install in a ventilated, shaded place, ideally 15 to 25 °C | Attics, sun-facing walls, unheated sheds in winter |
| Let it reach full charge regularly (helps balance and SOC calibration) | Leaving it at 100 % for weeks with no use |
| Set a sensible minimum state of charge in the inverter | Draining it to empty and leaving it there for days |
| Use the battery protocol in the inverter (CAN/RS485), not voltage-only mode | Charge voltages above Pylontech’s recommendation |
| Check cell spread and SOH every few months | Discovering a problem only when the inverter shows an error |
How to track your battery’s ageing
The difficulty is that the inverter shows a single state of charge for the whole stack. Ageing happens module by module, and a single tired module can limit the whole stack. To follow it, you need per-battery data from the BMS: SOH, cycle count, temperatures and cell voltages.
PylonCheck reads exactly that through the CONSOLE port of the master battery and keeps it in the cloud for three years, so you can see SOH and cell spread evolve over months, not just today’s values. It also emails you advice when cells drift apart. If you are buying a used battery or claiming under warranty, that history is valuable evidence.
For a one-off health check, follow the 10-point Pylontech battery check; to understand each value, see our diagnostics guide.