KG50 Motorola Moto One Hyper Replacement Battery 3.85V 3900mAh

Motorola Moto One Hyper (XT2027 Series) — 3.85V Li-Polymer Replacement Battery (KG50)

This 3.85V, 3900mAh Li-Polymer cell replaces the OEM KG50 battery in the Motorola Moto One Hyper. It fits the XT2027, XT2027-1, and XT2027-2 variants. Swap it in when the original cell can no longer hold a charge or drops voltage unexpectedly under screen or modem load.

• XT2027 series fit: All XT2027 variants share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The KG50 part number is consistent across the full lineup, so one cell covers all three sub-models without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on an XT2027-1 unit. The BMS accepted the cell cleanly, thermal cutoff triggered correctly at the expected ceiling, and the charge IC completed a full cycle without flagging an error state.
• 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 map the new cell's discharge curve before high-current charging runs into an uncalibrated coulomb counter.

Sudden shutdown at 20–30% on the Moto One Hyper after a cell swap

The XT2027's fuel gauge IC retains the discharge curve from the old, degraded cell. When a new cell is installed, the IC's calibration no longer matches actual cell voltage under load. The modem and display together draw enough current to cause a brief voltage sag — if the IC reads that sag as the cutoff floor, it shuts the phone down even though charge remains. One full slow-charge cycle forces the IC to relearn the new cell's voltage-versus-capacity curve and eliminates the false shutdown.

USB-PD fast charging not activating on the first cycle after replacement

After a cell swap, the charge IC on the Moto One Hyper defaults to a conservative trickle current until it confirms the new cell's internal resistance is within range. On the first cycle, the BMS may reject the USB-PD handshake and fall back to standard 5V charging. This is a protection response, not a fault with the charger or the replacement cell. Completing one full standard charge cycle re-establishes the handshake, and fast charging activates normally from the second cycle onward.