About this replacement
Fey Elektronik PA-LN2 — 3.7V Li-ion Replacement Battery
This is a 3.7V, 2200mAh (8.14Wh) Li-ion battery pack built to fit the Fey Elektronik PA-LN2. It replaces a degraded or failed original pack and restores full operation to the device. Dimensions are 52.60 × 34.20 × 11.00mm — verify these against your existing pack before ordering.
- PA-LN2 fit: This pack matches the PA-LN2's voltage rail and physical envelope. The connector orientation and cell configuration align with the original spec, so the device's charge circuit sees the pack as expected.
- Bench tested on actual hardware: We ran this pack through charge and discharge cycles on the bench. The BMS held cutoff at the correct thresholds and the pack reached rated capacity after the first full cycle.
- First-cycle calibration: If your PA-LN2 uses an integrated fuel gauge, run one complete charge-discharge cycle immediately after installation. New cells arrive at storage voltage, and the gauge needs a full cycle to map capacity accurately against the fresh cells.
Pack running below 3.7V on first use
Replacement packs ship at storage voltage — typically around 3.6V or lower — to reduce cell stress during transit. This is normal and not a fault. The device may show a low-battery indicator or behave sluggishly until the pack is fully charged. Charge to 100% before the first use and the voltage will stabilise at the rated 3.7V nominal.
Pack not reaching full charge on the first cycle
On the first charge cycle, the PA-LN2's charge IC may apply a reduced current to new cells as a conditioning step — this can cause the charge cycle to terminate earlier than expected. The pack is not defective. Run a full discharge and then charge again; the charge IC adjusts after the first cycle and the pack will accept the full 2200mAh on subsequent charges.