About this replacement
Motorola Moto 360 — 3.7V Li-Polymer Replacement Battery (WX30 / SNN5950A)
This 3.7V, 240mAh lithium-polymer cell replaces the OEM battery in the Motorola Moto 360 smartwatch. It fits the first-generation Moto 360 circular smartwatch running Wear OS. Dimensions are 29.88 x 28.78 x 4.23mm — check these against your cell before installing.
- Moto 360 compatibility: The WX30, SNN5950A, and SNN5951A part numbers all reference the same cell format used across Moto 360 production runs. The connector pinout and BMS handshake are identical across these variants, so any of these OEM numbers confirms fitment.
- Bench tested on actual hardware: We ran this cell on a Moto 360 unit and confirmed the BMS accepted the new cell without fault codes. The fuel gauge IC registered charge state correctly after a full charge cycle from near-zero.
- Post-swap charging requirement: After fitting this cell, place the watch on its magnetic charger immediately and bring it to 100% before using it. The fuel gauge IC on the Moto 360 loses its voltage reference when the cell is removed. Without a full charge cycle from near-zero, the percentage readout will be inaccurate or stuck.
Why the Moto 360 fuel gauge reads wrong after a cell swap
The Moto 360 uses a coulomb-counting fuel gauge IC that tracks charge in and out relative to a learned reference point. When you remove the battery, that reference is wiped. The IC then estimates state-of-charge from open-circuit voltage alone, which is imprecise on lithium-polymer cells — especially a new one with a slightly different internal impedance profile. The only way to re-establish an accurate reference is a full charge from near-zero, which resets the upper boundary the IC uses for all future percentage calculations.
Watch not pairing to phone after battery replacement
Removing the battery cuts power to the BLE radio mid-session, which drops the active pairing bond stored in volatile memory. The phone still shows the watch as paired, but the watch no longer holds a matching bond key. Open the Wear OS app on your phone, tap the watch name, select "Forget device," then re-pair from scratch. This takes about two minutes and fully restores notification sync and health data logging.