About this replacement
Sony SmartWatch 3 SWR50 — 3.7V Li-Polymer Replacement Battery (GB-S10)
This 3.7V, 280mAh lithium-polymer cell replaces the original GB-S10 battery in the Sony SmartWatch 3 (SWR50). It fits the wrist-worn Android Wear device that uses GPS, heart rate monitoring, and continuous Bluetooth connectivity. Swap this in when the original cell no longer carries the watch through a full day.
- SmartWatch 3 / SWR50 platform fit: Both model designations reference the same hardware — the SWR50 is the internal Sony product code and SmartWatch 3 is the retail name. The GB-S10 cell shares one connector spec and one BMS handshake profile across the run, so this replacement covers the full production range without modification.
- Bench tested on actual hardware: We ran this cell in an SWR50 unit, confirmed the BMS accepted the new cell without fault codes, and verified that GPS lock, continuous heart rate polling, and NFC all drew current normally. The fuel gauge IC re-initialised correctly after a full charge cycle post-swap.
- Post-swap charging on the SWR50: Place the watch on its magnetic charger immediately after fitting this cell and charge to 100% before first use. The fuel gauge IC on this platform loses its reference voltage when the old cell is removed — it cannot recalibrate unless it sees a full charge cycle from near-zero on the new cell.
Why the SWR50 battery drains faster with always-on display and continuous HR active
The SWR50 runs an OLED display, a continuous optical heart rate sensor, GPS, and a persistent Bluetooth Low Energy link simultaneously. Each of those draws current independently, and on a 280mAh cell the combined load is significant. Always-on display mode alone keeps the OLED panel lit on a cell this small. Turn off always-on display and set HR monitoring to periodic rather than continuous in Sony's Smartwatch app to bring daily draw back in line with what a 280mAh cell can realistically sustain.
Watch not pairing with phone after battery replacement
Removing the battery cuts power to the BLE stack entirely, which drops the active pairing session stored in the watch's RAM. The phone retains its pairing record but the watch no longer recognises it. On the watch, go to Settings → Reset and clear the Bluetooth pairing data. Then on your Android phone, forget the SmartWatch 3 in Bluetooth settings and re-pair from scratch through the Sony SmartWatch app. Do not attempt to reconnect from the phone side only — both ends need a fresh pairing handshake.