Nokia 6300 4G Replacement Battery BL-4AX 3.7V 1500mAh

Nokia 6300 4G / 8000 4G — 3.7V Li-ion Replacement Battery (BL-4AX)

This is a 3.7V, 1500mAh Li-ion replacement battery for the Nokia 6300 4G and 8000 4G smartphones, including variants TA-1286 and TA-1291. It replaces OEM part numbers BL-4AX and BL-4XL. Physical dimensions are 69.40 × 44.00 × 4.20mm — confirm these against your existing cell before ordering.

• 6300 4G and 8000 4G platform fit: Both handsets run the same battery bay geometry and share the BL-4AX designation. The connector pinout and BMS communication protocol are identical across TA-1286, TA-1291, and the broader variant range, so one cell covers the full lineup without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the 6300 4G platform. The BMS handshake completed correctly, charge acceptance was confirmed at the expected 4.2V cutoff, and the protection circuit tripped at the correct undervoltage threshold during discharge testing.
• Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before any high-current session pushes current into an uncalibrated state.

Sudden shutdown at 20–30% on the Nokia 6300 4G after a cell swap

This happens because the fuel gauge IC is still calibrated to the old cell's discharge curve. The new cell hits a voltage cliff — it cannot sustain rail voltage under combined modem and display load — before the reported percentage reaches zero. The phone interprets the voltage drop as a hard fault and shuts down. One full discharge-to-charge cycle at standard rate forces the coulomb counter to relearn the new cell's actual capacity endpoints and typically resolves the early cutoff.

Phone shows wrong battery percentage after replacement

The fuel gauge IC on the 6300 4G stores learned discharge data from the previous cell. Swapping the cell doesn't reset that stored curve automatically. As a result, percentage readings can jump erratically or plateau at an incorrect figure for the first several cycles. Run two full charge and discharge cycles without interruption — by the end of the second cycle, the coulomb counter resets its reference points against the new cell and reported percentages stabilise.