Nokia BL-5B 5300 XpressMusic Replacement Battery 3.7V 750mAh

Nokia 5300 XpressMusic / 2610 / 3220 — 3.7V Li-ion Replacement Battery (BL-5B)

This is a 3.7V, 750mAh Li-ion replacement for the Nokia BL-5B cell. It fits the 5300 XpressMusic, 2610, 3220, 3230, and over 20 additional Nokia handsets that share the same BL-5B footprint and connector. Physical dimensions are 46.20 × 34.14 × 5.68mm — measure your original before ordering if you are unsure.

• BL-5B platform compatibility: Nokia used the BL-5B cell across a wide range of mid-2000s handsets because they share the same three-contact connector, voltage rail, and physical envelope. One cell works across all of them without modification.
• Bench tested on actual hardware: We ran this cell on a 5300 XpressMusic and monitored BMS handshake and charge termination. The protection circuit responded correctly to charge cutoff at 4.2V and low-voltage lockout below 2.5V per cell.
• Fuel gauge recalibration on first install: After fitting this cell, run one full discharge down to auto-shutdown and charge back to 100% without interruption. The 5300's fuel gauge IC calibrates its coulomb counter against that first complete cycle — skipping it causes erratic percentage readings for days.

Why the 5300 XpressMusic reports wrong battery percentage after a cell swap

The 5300 uses a fuel gauge IC that tracks charge state by counting coulombs against a stored discharge curve. That curve was built around the original aged cell, not a new one. When a fresh 750mAh cell goes in, the IC's reference points no longer match actual cell behaviour, so it displays percentages that jump or stall. One full discharge-to-shutdown followed by an uninterrupted charge to 100% forces the IC to rewrite its reference curve against the new cell. After that cycle, percentage readings stabilise.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff symptom, not a capacity fault. Under the load of the backlight, audio output, and radio simultaneously — common during music playback with the screen active — cell voltage can sag below the BMS cutoff threshold even when the fuel gauge still shows charge remaining. The fuel gauge IC is reading an uncalibrated state-of-charge, so it reports 25% while actual terminal voltage has already dropped to the cutoff point. Complete the full recalibration cycle first; if shutdowns continue after that, check that the battery contacts on the phone chassis are clean and making firm contact — oxidised contacts increase resistance and worsen voltage sag under load.