Motorola Razr 2022 NM50 Replacement Battery 3.89V 2600mAh

Motorola Razr 2022 — 3.89V Li-Polymer Replacement Battery (NM50)

This is a 3.89V, 2600mAh lithium-polymer battery for the Motorola Razr 2022 smartphone, covering models XT2251 and XT2251-1. OEM part numbers NM50 and SB18D44719 apply. It replaces the original cell when capacity has faded or the battery no longer holds a usable charge.

• Razr 2022 and Razr 5G 3rd Gen compatibility: Both the XT2251 and XT2251-1 share the same battery bay geometry, connector pinout, and BMS handshake protocol — one cell fits both variants without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a Razr 2022 unit. The BMS accepted the cell without fault flags, and the charge IC stepped through trickle, CC, and CV phases as expected.
• Fuel gauge recalibration on first cycle: 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 the Razr 2022 after a cell swap

The Razr 2022 uses a coulomb counter that was calibrated to the original cell's discharge curve. When a new cell goes in, that curve no longer matches. The fuel gauge reads 25% while the actual cell voltage is already near the BMS cutoff threshold — typically around 3.0V under modem or display load. The phone shuts down not because the cell is weak, but because the gauge and the real voltage diverge at the knee of the discharge curve. One full discharge-to-shutdown followed by a complete charge resets the coulomb counter and eliminates these premature cutoffs.

USB-PD fast charge not triggering on the first cycle after replacement

Some Razr 2022 units will not negotiate fast charge on the first cycle with a new cell — the charge IC defaults to standard 5V/1A until it has seen at least one full charge cycle. This is a protective behaviour tied to the BMS handshake, not a fault with the charger or cable. Use a standard charge for the first full cycle, then reconnect with the fast charger. Fast charge should activate normally from the second cycle onward.