Rollei 10050 Replacement Battery 3.7V 900mAh Li-ion

Rollei 10050 Series — 3.7V Li-ion Replacement Battery

This is a 3.7V, 900mAh (3.33Wh) lithium-ion cell for the Rollei 10050, 10051, 10052, and 10053 smartphones. It replaces an original cell that no longer holds a charge or causes unexpected shutdowns. Physical dimensions are 46.20 × 34.14 × 5.68mm — confirm these against your existing cell before fitting.

• 10050 series compatibility: These four models share the same battery bay dimensions, connector pinout, and 3.7V nominal voltage rail. The BMS communication protocol is consistent across the series, so one cell covers all listed variants.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the 10050 platform. The BMS accepted the cell without error flags, and the charge IC completed a full CC/CV charge cycle to cutoff without thermal events.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell.

Sudden shutdown at 20–30% on a replacement cell

A new cell has a slightly different discharge curve than the worn cell the fuel gauge IC was calibrated to. At 20–30% displayed charge, the phone's voltage model predicts more capacity than the new cell can actually deliver under modem or screen load. Voltage drops below the BMS cutoff threshold before the OS registers zero percent. One full discharge-to-shutdown followed by an uninterrupted charge to 100% resets the coulomb counter and resolves this.

Phone reports incorrect battery percentage after cell swap

The fuel gauge IC stores a learned discharge profile from the original cell. After swapping to a new cell, the stored profile no longer matches the actual voltage-to-capacity curve, so percentage readings jump or stall at fixed values. This is not a fault with the replacement cell — it is the IC recalibrating. Run two full discharge-charge cycles without interruption, and the reported percentage will track accurately by the third cycle.