BL-5H Microsoft Lumia 630 Replacement Battery 3.7V 1800mAh

Microsoft Lumia 630 / 636 / 638 — 3.7V Li-ion Replacement Battery (BL-5H)

This is a 3.7V, 1800mAh Li-ion replacement battery for the Microsoft Lumia 630, Lumia 630 Dual SIM, Lumia 636, and Lumia 638. It uses Nokia's BL-5H form factor and drops into the same battery bay without modification. Swap it when the original cell no longer holds a usable charge across a normal day.

• Lumia 630 / 636 / 638 platform fit: These four handsets share the same battery bay dimensions, contact layout, and BMS handshake tied to the BL-5H cell. One replacement covers all of them without adapter or firmware changes.
• Bench tested on actual hardware: We cycled this cell on a Lumia 630 board and confirmed the BMS negotiated charge cutoff correctly at 4.2V. Discharge curve held steady through repeated load tests without early BMS trip.
• Fuel gauge recalibration on first use: On first use after installation, run one full discharge down to auto-shutoff then charge uninterrupted to 100% before resuming normal use. This lets the coulomb counter recalibrate against the new cell's discharge curve and prevents erratic percentage readings.

Why the Lumia 630 reports wrong battery percentage after a cell swap

The Lumia 630 uses a coulomb counter that builds its fuel gauge model from the cell it was calibrated against — the original BL-5H. A new cell has a slightly different internal resistance and discharge curve, so the counter's stored model no longer maps to actual state of charge. The result is percentage readings that are off by 10–20% or jump unexpectedly. One full discharge-to-shutoff followed by a full uninterrupted charge resets the counter's reference points against the replacement cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops below the modem's or display's minimum operating threshold under peak load, even though the fuel gauge still shows charge remaining. A new cell with an uncalibrated fuel gauge will show 25% while actual voltage has already collapsed below 3.4V under screen-on or LTE load. The BMS cuts the circuit to protect the cell, and the phone shuts off without warning. After the first full calibration cycle described above, the reported percentage will align more closely with real cell voltage and shutdowns at false-high percentages should stop.