About this replacement
Nokia G50 / TA-1358 / TA-1390 — 3.85V Li-Polymer Replacement Battery (P660)
This is a 3.85V, 4950mAh Li-Polymer battery for the Nokia G50 smartphone, covering model variants TA-1358, TA-1390, and TA-1370. It uses OEM part number P660 and matches the original cell format at 93.70 × 65.00 × 4.50mm. Swap it in when the factory cell no longer holds a charge through a full day of use.
- G50 variant coverage: The TA-1358, TA-1390, and TA-1370 all share the same battery bay dimensions, connector pinout, and BMS handshake protocol — one P660 cell fits the entire G50 range without modification.
- Bench tested on actual hardware: We ran this cell through charge-discharge cycles on G50 hardware. The BMS accepted the USB-PD handshake correctly, held voltage above 3.6V through mid-cycle load, and triggered the low-voltage cutoff at the expected threshold without false trips.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. The G50's fuel gauge IC calibrates its coulomb counter against the new cell's discharge curve — running a slow cycle first prevents the percentage jumps and early shutdowns that happen when the IC is still mapped to the old cell's characteristics.
Sudden shutdown at 20–30% on the Nokia G50 after a cell swap
The G50's fuel gauge IC builds a discharge model from the original cell's voltage curve. When a new cell goes in, the IC still uses that old model — and the two curves diverge most sharply in the lower charge range. Below 30%, the modem and display pull enough current that the new cell's actual voltage drops below the emergency cutoff threshold before the reported percentage reaches zero. The phone shuts off to protect the cell, even though the display says 20–28% remaining. One full slow discharge-to-3.5V followed by a full charge resets the coulomb counter and brings the reported percentage back in line with actual cell state.
USB-PD fast charge not activating on the first cycle after replacement
Some G50 units will not accept the USB-PD fast charge handshake on the very first cycle after a battery swap. The charge IC briefly defaults to standard 5V/0.9A charging while it verifies the new cell's impedance signature. This is normal behaviour — it is not a fault with the replacement cell or the charger. Plug in, let the first charge complete fully at standard rate, then disconnect and reconnect the charger. The USB-PD protocol should negotiate correctly from the second cycle onward at the expected voltage.