BlackBerry Curve 9370 EM1 Replacement Battery 3.7V 1000mAh

BlackBerry Curve 9370 / 9360 / 9350 — 3.7V Li-ion Replacement Battery (EM1 / BAT-34413-003)

This is a 3.7V, 1000mAh Li-ion replacement battery for the BlackBerry Curve 9350, 9360, and 9370 smartphones. It replaces OEM part numbers EM1, BAT-34413-003, ACC-39508-201, and ACC-39508-301. The cell matches the original form factor at 42.00 × 39.20 × 5.00mm and seats directly in the battery bay.

• Curve 9350 / 9360 / 9370 platform fit: These three Curve models share the same battery bay dimensions, connector pinout, and BMS handshake protocol — one cell covers all three. The EM1 designation is consistent across BlackBerry's own part number variants for this platform.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on a Curve 9370 unit. The BMS accepted the cell without fault codes, charge termination fired correctly at 4.2V, and the protection circuit tripped cleanly at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first cycle: After fitting this cell, run one complete discharge down to auto-shutdown, then charge uninterrupted to 100% before normal use. The Curve's fuel gauge IC calibrates its coulomb counter against this first full cycle — skipping it causes the percentage display to read inaccurately for weeks.

Why the Curve 9370 shuts down suddenly at 20–30% battery remaining

The Curve 9370 runs its radio modem and display simultaneously during heavy messaging or email sync. That combined load draws a current spike the cell must sustain while holding voltage above the BMS cutoff threshold. An aged or deeply discharged replacement cell has higher internal impedance, so voltage sags sharply under that spike even when the fuel gauge still reads 25%. The BMS reads the instantaneous voltage drop — not the fuel gauge percentage — and triggers shutdown to protect the cell. A full recalibration cycle after installation tightens the fuel gauge IC's model so it factors in the cell's actual impedance and warns you earlier.

Battery percentage jumping erratically after fitting the new cell

The fuel gauge IC on the Curve platform stores a learned discharge curve from the previous cell. When a new cell goes in, that stored curve no longer matches the actual cell chemistry and impedance. The IC then makes large corrections mid-cycle as it detects the mismatch, which shows up as the percentage skipping — jumping from 45% to 62%, or dropping 10% in two minutes. Run one full uninterrupted discharge to auto-shutdown, followed by a full charge to 100%. After that single cycle the coulomb counter resets its baseline and percentage tracking stabilises.