Pioneer PAP4322 Duo Replacement Battery 3.7V 1650mAh Li-ion

Pioneer PAP4322 Duo / E60W — 3.7V Li-ion Replacement Battery

This is a 3.7V 1650mAh Li-ion cell for the Pioneer PAP4322 Duo and E60W smartphones. It replaces the original battery when capacity has dropped to the point where the phone can no longer hold a usable charge across a normal day. Physical dimensions are 51.36 × 50.89 × 5.03mm — verify these against your existing cell before fitting.

• PAP4322 Duo and E60W fit: Both phones share the same battery bay dimensions, voltage rail, and connector pinout, so a single cell covers both models. The BMS communicates over the same two-wire interface on each device.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench and confirmed the BMS handshake completes correctly. Charge acceptance was normal from the first cycle, with no overcurrent trips or protection circuit lockouts observed.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging is introduced.

Sudden shutdown at 20–30% on the PAP4322 Duo after a cell swap

This is a voltage cliff problem, not a capacity problem. Under peak load — active modem, screen at full brightness, background sync — the new cell's internal resistance causes voltage to sag below the BMS cutoff threshold before the fuel gauge reads empty. The phone interprets this as a hard undervoltage event and shuts down even though the reported percentage still looks healthy. One full discharge-charge cycle at standard rate recalibrates the coulomb counter and the shutdowns typically stop.

Phone shows wrong battery percentage after fitting the replacement cell

The fuel gauge IC on the PAP4322 Duo stores a discharge curve learned from the original cell. When a new cell goes in, the IC is still referencing the old curve, so percentage readings are inaccurate — often reading high early and then dropping sharply. The fix is one complete discharge to automatic power-off followed by a full uninterrupted charge to 100%. After that single cycle the coulomb counter resets its reference and percentage tracking stabilises.