Polaroid Pro 1021 Replacement Battery BAT05BPR 3.7V 700mAh

Polaroid Pro 1021 — 3.7V Li-ion Replacement Battery (BAT05BPR)

This is a 3.7V Li-ion cell rated at 700mAh (2.59Wh), built to the same footprint as the original BAT05BPR. It fits the Polaroid Pro 1021 handset. Use it when the original cell no longer holds a charge or the phone fails to power on at all.

• Pro 1021 fitment: The Pro 1021 uses a compact 46.63 x 33.76 x 4.57mm cell with a connector keyed to the phone's charge IC and fuel gauge IC. Both must recognise the cell for charging and percentage reporting to work correctly. This replacement matches that connector and cell profile exactly.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the Pro 1021 platform. The BMS accepted the cell without fault flags, the charge IC ramped to CC/CV without interruption, and the fuel gauge IC tracked state of charge across the full curve.
• First-cycle fuel gauge reset: On first use after installation, disable fast charging if the option is available and run one complete discharge-to-charge cycle. This lets the fuel gauge IC map its coulomb counter to the new cell's discharge curve before it reports percentage to the OS.

Why the Pro 1021 reports wrong battery percentage after a cell swap

The Pro 1021 uses a fuel gauge IC that builds its state-of-charge model from the discharge history of the original cell. When you install a new cell, that learned curve no longer matches the actual chemistry. The IC reads voltage against an outdated map and reports a percentage that can be off by 15–25%. One full discharge down to automatic shutdown followed by a complete charge to 100% forces the coulomb counter to recalibrate against the new cell. After that cycle, percentage readings stabilise.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC is still running the old cell's voltage-to-capacity curve. The new cell hits a voltage cliff — typically around 3.5V under modem or screen load — before the reported percentage reaches zero. The phone's protection circuit reads an undervoltage condition and shuts down immediately. The fix is the same full recalibration cycle: drain the phone to shutdown, then charge uninterrupted to 100%. If the shutdowns continue after two full cycles, check that the connector is fully seated and the cell resting voltage reads at least 3.6V with a multimeter before reinstallation.