Nokia BLB-2 8210 Replacement Battery 3.7V 750mAh

Nokia 8210 / 8310 Series — 3.7V Li-ion Replacement Battery (BLB-2)

This is a 3.7V Li-ion replacement battery carrying OEM part number BLB-2. It fits the Nokia 8210, 8250, 8270, 8310, and over 15 additional Nokia models sharing the same battery bay and connector format. Capacity is 750mAh (2.78Wh), matching the original cell specification.

• 8210 / 8310 platform compatibility: These models share the same voltage rail, physical footprint, and BLB-2 connector pinout. The BMS handshake is consistent across the series, so the phone's charge IC accepts the replacement cell without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the 8210 platform. The BMS held cutoff correctly at both ends of the charge curve, and the charge IC did not flag a fault during the first full cycle.
• Fuel gauge recalibration on first use: After fitting this battery, run one complete discharge-charge cycle before relying on the percentage readout. The phone's fuel gauge IC was calibrated to the old cell's discharge curve — it needs one full pass against the new cell to report accurately.

Why the Nokia 8210 reports the wrong battery percentage after a cell swap

The 8210 uses a basic coulomb-counting fuel gauge IC that builds its percentage model from the discharge curve of whichever cell is fitted. When you swap in a new BLB-2 cell, the IC is still referencing data from the old, degraded cell. Until it completes one full discharge-charge cycle with the replacement, the percentage display will read high or jump between values. This is not a fault with the new cell — it corrects itself after a single calibration cycle.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC has not yet recalibrated its low-voltage threshold to the new cell's discharge curve. The phone calculates 20–30% remaining based on the old cell's steeper voltage drop, but the new cell hits the BMS low-cutoff point — typically around 3.0V — sooner than the display predicts. The phone shuts off to protect the cell. One full discharge down to automatic cutoff, followed by a full charge, lets the IC reset its endpoint model and eliminates the false cutoff.