Pantech Breeze IV Replacement Battery PBR-40C 3.7V 750mAh

Pantech Breeze IV / P2050 — 3.7V Li-ion Replacement Battery (PBR-40C)

This is a 3.7V 750mAh Li-ion cell built to replace the original PBR-40C battery in the Pantech Breeze IV (P2050). It fits the Breeze IV, Breeze 4, and P2050 variants — all share the same form factor and connector. Dimensions are 54.24 × 41.84 × 4.19 mm, matching the OEM battery bay exactly.

• Breeze IV / Breeze 4 / P2050 fit: All three model designations use the same battery bay, connector pinout, and BMS communication protocol — one cell covers every variant without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the P2050 platform. The BMS handshake completed correctly on the first cycle, and the protection circuit tripped at the expected low-voltage cutoff threshold.
• Fuel gauge recalibration after swap: On first use after installing this cell, run one complete discharge down to auto-shutoff, then charge uninterrupted to 100%. This gives the phone's fuel gauge IC a clean reference curve for the new cell — skipping this step causes erratic percentage readings early on.

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

The Breeze IV's fuel gauge IC stores a discharge curve calibrated to the original cell's internal resistance and voltage profile. A new cell has a different curve, so the IC misreads remaining capacity under screen and modem load. When actual cell voltage drops below roughly 3.5V under load, the phone shuts down — even though the gauge still shows 20–30%. One full discharge-to-shutoff cycle followed by a complete uninterrupted charge lets the coulomb counter reset against the new cell and clears this behaviour.

Phone won't power on after the replacement battery sat in storage

Li-ion cells self-discharge during storage. If this battery sat below 2.5V per cell before installation, the BMS enters lockout mode and blocks charge current to prevent damage. The phone will show no sign of life — no charging indicator, no boot screen. Connect the phone to a wall charger and leave it undisturbed for 15–20 minutes; the charge IC trickle-charges the cell back above the BMS re-enable threshold of approximately 2.9V. After that, a normal charge cycle proceeds.