BlackBerry Pearl 3G F-M1 Replacement Battery 3.7V 1100mAh

BlackBerry Pearl 3G — 3.7V Li-ion Replacement Battery (F-M1)

This is a 3.7V, 1100mAh Li-ion cell that replaces the original F-M1 battery in the BlackBerry Pearl 3G, Pearl 2, Pearl 9100, and Pearl 9105. It also fits seven additional Pearl series handsets that share the same form factor and connector. Dimensions are 51.12 × 36.78 × 5.56mm — measure your original before ordering if you are unsure.

• Pearl series compatibility: Every model in this fit list runs the same voltage rail and uses the same physical connector with identical BMS handshake requirements. One cell covers the full Pearl family without modification.
• Bench tested on actual hardware: We ran this cell in a Pearl 9100 and monitored the BMS through charge and discharge cycles. The protection circuit held cutoff correctly at both ends, and charge termination tripped cleanly at 4.2V.
• Fuel gauge recalibration on first install: After fitting, let the phone discharge fully to auto-shutdown, then charge uninterrupted to 100% before normal use. The Pearl's coulomb counter needs one complete cycle against the new cell's discharge curve to report accurate percentages.

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

This happens because the fuel gauge IC in the Pearl 9100 and 9105 is still calibrated to the old cell's discharge curve. When voltage drops faster than the IC expects under modem or display load, the phone hits the hardware cutoff before the percentage counter reaches zero. The OS sees a cliff, not a slope, and shuts down mid-use. One full discharge-to-shutdown followed by a full uninterrupted charge resets the coulomb counter against the new cell's actual curve and eliminates the false cutoff.

Phone stays at a fixed percentage for long stretches, then drops sharply

This is the fuel gauge IC reading stale reference data — it holds a percentage longer than it should because the cell's voltage curve does not match its calibration table. The gauge then corrects itself abruptly when voltage falls outside the expected window. This is not a cell defect. Perform a single full discharge cycle: drain the phone to automatic shutdown, then charge continuously to 100% without interruption. After that cycle, the gauge tracks the new cell accurately and the erratic jumps stop.