Huawei Mate 20 X Compatible Battery HB3973A5ECW 3.85V 4900mAh

Huawei Mate 20 X / Honor Note 10 — 3.85V Li-Polymer Replacement Battery (HB3973A5ECW)

This is a 3.85V, 4900mAh (18.87Wh) Li-Polymer cell for the Huawei Mate 20 X and Honor Note 10. It fits the EVR-L29 and EVR-AL00 hardware variants and shares the OEM part number HB3973A5ECW. When the original cell degrades past the point where the device holds a usable charge, this replacement restores full operating capacity.

• Mate 20 X and Honor Note 10 fitment: Both devices run the same battery bay dimensions and connector pinout. The BMS handshake protocol and 3.85V nominal voltage rail are identical across the EVR-L29, EVR-AL00, and Honor Note 10 PCBs, so one cell covers the full compatibility list.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Mate 20 X unit. The BMS accepted the cell without rejecting it at the authentication handshake, and the charge IC brought it to 4.4V cutoff cleanly with no thermal events.
• Fuel gauge recalibration on first use: Disable SuperCharge for the first complete discharge-to-charge cycle after installation. This gives the fuel gauge IC time to map the new cell's discharge curve before high-current charging pushes current into an uncalibrated coulomb counter.

Sudden shutdown at 20–30% on the Mate 20 X after a cell swap

The Mate 20 X's fuel gauge IC retains the discharge curve of the old, degraded cell in its coulomb counter. A new cell with a steeper voltage cliff under modem or display load can drop below the shutdown threshold before the reported percentage reaches zero. The phone interprets the voltage sag as a hard low-battery cutoff even though the gauge still shows charge remaining. Running one full discharge cycle without SuperCharge lets the IC rewrite its internal capacity estimate against the actual new cell curve, and the shutdowns typically stop.

USB-PD or SuperCharge not engaging on the first charge after installation

On the first cycle after installation, the Mate 20 X charge IC sometimes falls back to standard 5V charging and refuses to negotiate the SuperCharge protocol with a new, unconditioned cell. This happens because the BMS flags an uncalibrated cell state and limits the current path as a safety measure. Charge the device fully at standard rate on that first cycle and unplug at 100%. On the second cycle, SuperCharge should re-engage and the negotiation handshake will complete at the correct voltage step.