Lenovo Phab 2 Pro L16D1P31 Replacement Battery 3.82V 4000mAh

Lenovo Phab 2 Pro — 3.82V Li-Polymer Replacement Battery (L16D1P31)

This is a 3.82V, 4000mAh Li-Polymer cell for the Lenovo Phab 2 Pro (PB2-690N). It replaces the original L16D1P31 pack when the existing cell no longer holds adequate charge. Capacity is rated at 15.28Wh, matching the factory specification for this device.

• Phab 2 Pro / PB2-690N fitment: The Phab 2 Pro uses a dedicated connector pinout and BMS handshake tied to the L16D1P31 spec. This replacement matches that voltage rail and pack geometry — 73.82 × 60.66 × 4.65mm — so the cell seats correctly without forcing the adhesive frame or stressing the flex connector.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the PB2-690N platform. The BMS accepted the pack without faults, charge termination triggered correctly at full voltage, and the protection circuit responded as expected to load cutoff thresholds.
• Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging for one complete discharge-to-charge cycle. The Phab 2 Pro's fuel gauge IC was calibrated to the old cell's discharge curve. Running one slow cycle lets the coulomb counter re-anchor to the new cell before fast charge current is applied to an uncalibrated pack.

Sudden shutdown at 20–30% on the Phab 2 Pro after a cell swap

This is a voltage cliff symptom. Under combined modem, screen, and Tango sensor load — the Phab 2 Pro's AR hardware draws hard bursts — the new cell's internal resistance causes a voltage dip the BMS reads as a cutoff event, even though the state-of-charge display still shows 20–30%. The fuel gauge IC hasn't yet mapped the new cell's discharge curve accurately, so it's working from stale calibration data. Run two full discharge-charge cycles without fast charging to let the gauge re-learn the voltage-to-capacity relationship on the replacement cell.

Phone reports wrong battery percentage after L16D1P31 replacement

The Phab 2 Pro's fuel gauge IC stores discharge curve data from the original cell — impedance, voltage slope, and capacity endpoints. A new cell has different characteristics, so the IC's coulomb counter reads against the wrong baseline and reports inaccurate percentages. Charge the device to 100% until the charger terminates naturally, then discharge fully until the phone shuts off from low voltage. Repeat this once more. After two full cycles the gauge recalibrates and percentage readings stabilise. Do not interrupt either cycle with a mid-charge top-up.