About this replacement
Samsung Galaxy Watch 46mm — 3.85V Li-Polymer Replacement Battery (EB-BR800ABU)
This 3.85V, 450mAh Li-Polymer cell replaces the original battery in the Samsung Galaxy Watch 46mm (SM-R800 and SM-R805). It fits the same cavity, uses the same connector, and works with the watch's existing charging and battery management circuitry. Swap it in when the original cell no longer holds a full day of use.
- SM-R800 and SM-R805 compatibility: Both the Bluetooth and LTE variants of the Galaxy Watch 46mm share the same battery bay, connector pinout, and BMS handshake protocol. One cell covers both.
- Bench tested on actual hardware: We ran this cell through a full charge cycle on an SM-R800 unit. The BMS accepted the cell without fault flags, fuel gauge initialised correctly after a complete charge, and all sensors reported normal draw.
- Post-swap charging requirement: After fitting this cell, place the watch on its magnetic charger immediately and charge to 100% before wearing it. The fuel gauge IC on the SM-R800 platform cannot set an accurate reference point without a full charge cycle from near-zero following a cell swap — skipping this step causes persistent percentage errors.
Always-on display and continuous heart rate monitoring draining the Galaxy Watch 46mm faster than expected
The SM-R800 draws measurably more current when Always-On Display (AOD) is active alongside continuous heart rate monitoring. AOD keeps the AMOLED panel partially lit at all times, while the optical HR sensor pulses every second in continuous mode — both run from this 450mAh cell. A new cell will not change that draw profile; it simply gives you a full-capacity starting point. Turn off AOD or switch HR monitoring to "every 10 minutes" in the Samsung Health app to see a significant difference in daily drain.
Watch not pairing to phone after battery replacement
Removing the battery ends the active BLE session between the watch and the Galaxy Wearable app — the phone does not automatically reconnect when power returns. The watch and phone both retain their pairing records, but the session needs to be re-established manually. Open the Galaxy Wearable app on your phone, tap the watch name, and select "Reconnect." If the app shows the watch as unavailable, toggle Bluetooth off and back on from the phone's quick settings panel.