BL-L5J Nokia 105 2023 Replacement Battery 3.7V 1000mAh

Nokia 105 2023 — 3.7V Li-ion Replacement Battery (BL-L5J)

This is a 3.7V, 1000mAh Li-ion replacement battery for the Nokia 105 2023 feature phone. It uses the BL-L5J form factor and slots directly into the original battery compartment. Voltage and cell dimensions match the OEM spec: 53.25 × 34.00 × 5.00mm.

• Nokia 105 2023 fit: The 105 2023 runs a low-draw hardware platform — basic voice calls, SMS, and standby. The BL-L5J cell is the sole battery format Nokia specified for this revision. No adapter or modification is needed; the connector and physical envelope are unchanged from the factory part.
• Bench tested on actual hardware: We ran this cell through charge and discharge on the Nokia 105 2023 platform. The BMS accepted the charge handshake on the first cycle, held voltage flat through standard call-load draws, and cut off cleanly at the low-voltage threshold without triggering premature shutdown.
• Fuel gauge recalibration on first use: After fitting this cell, run one full discharge to automatic power-off, then charge uninterrupted to 100% before use. The Nokia 105 2023 uses a basic coulomb counter that calibrates its percentage reading against the first complete cycle — skipping this step causes the phone to report inaccurate charge levels from the start.

Why the Nokia 105 2023 reports wrong battery percentage after a cell swap

The 105 2023 stores a discharge curve from the original cell in its fuel gauge IC. When a new cell goes in, the stored curve no longer matches the actual cell chemistry and internal resistance. The percentage display can read 40% and then drop to zero with no warning. One full discharge-to-cutoff cycle followed by a full uninterrupted charge resets the reference curve. After that single cycle, percentage tracking stabilises.

Phone won't power on after sitting in storage with a flat BL-L5J

If the BL-L5J cell has discharged below approximately 2.5V during storage, the BMS enters a lockout state and the phone shows nothing when you press the power button. Connect the phone to a charger and leave it for 20–30 minutes without attempting to power it on — the charge IC needs to push a trickle current into the cell before the BMS will release the lockout. Once the cell recovers above 3.0V, the phone boots normally.