I-Mate PC26A Smartphone Replacement Battery 3.7V 1150mAh

I-Mate Smartphone — 3.7V Li-ion Replacement Battery (PC26A)

This is a 3.7V, 1150mAh Li-ion replacement battery for the I-Mate Smartphone, using OEM part number PC26A. It slots into the original battery bay and restores the device to full operating condition. Capacity is rated at 4.26Wh, matching the original specification.

• I-Mate Smartphone compatibility: This battery uses the PC26A specification — same voltage rail, connector pinout, and BMS handshake protocol as the factory cell. No adapter or modification needed.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on I-Mate Smartphone hardware. The BMS accepted charge current correctly, voltage held steady under screen and modem load, and the protection circuit tripped at expected low-voltage cutoff thresholds.
• Fuel gauge recalibration after install: On first use after fitting this cell, disable fast charging and run one complete discharge-charge cycle before resuming normal use. This lets the fuel gauge IC map its coulomb counter against the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell.

Why the I-Mate Smartphone reports wrong battery percentage after a cell swap

The fuel gauge IC on this platform stores a learned discharge curve for the old cell in non-volatile memory. When a new cell is fitted, the IC compares incoming voltage readings against that stored curve — which no longer matches the new cell's actual chemistry profile. This causes the reported percentage to read high or low by a significant margin until the IC recalibrates. One full discharge down to automatic cutoff, followed by a full charge to 100%, resets the coulomb counter and re-anchors the fuel gauge to the new cell. After that cycle, percentage readings stabilise.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem or display draws a high-current burst and the cell voltage drops sharply — the BMS reads this as a low-voltage fault and cuts output before the gauge reaches 0%. A new cell with an uncalibrated fuel gauge makes this worse because the reported percentage is already inaccurate. The underlying cause is a voltage cliff: the cell's open-circuit voltage looks acceptable, but under load it sags past the BMS cutoff threshold. Run the recalibration cycle described above; if shutdowns persist after calibration, check that resting cell voltage reads above 3.6V with a multimeter before reinstalling.