Samsung Galaxy Watch Active 2 SM-R890 Replacement Battery EB-BR890ABY 3.88V 350mAh

Samsung Galaxy Watch Active 2 — 3.88V Li-Polymer Replacement Battery (EB-BR890ABY)

This 3.88V, 350mAh lithium-polymer cell replaces the original battery in the Samsung Galaxy Watch Active 2 and Galaxy Watch Active (SM-R890, SM-R870, SM-R875, SM-R890NZKCXAA). It restores full function to smartwatches with degraded cells that no longer hold a charge through a normal day. The cell cross-references OEM part numbers EB-BR890ABY, GH43-05066A, and EB-BR870ABY.

• Active 2 platform compatibility: The SM-R890 and SM-R870 series share the same 3.88V cell format, connector footprint, and BMS handshake protocol — which is why a single replacement cell covers both 40mm and 44mm Active 2 variants alongside the original Galaxy Watch Active.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on an SM-R890 unit. The BMS accepted the new cell without error flags, fuel gauge re-calibrated after a full charge, and all sensors — optical heart rate, accelerometer, barometer — remained active throughout discharge.
• Fuel gauge reset after swap: After fitting this cell, place the watch on its magnetic charger immediately and charge to 100% before first use. The fuel gauge IC on this platform cannot set an accurate reference point without a complete charge cycle from near-zero following a cell swap. Skip this step and the percentage readout will be unreliable for days.

Why the Galaxy Watch Active 2 drains a new cell faster than the old one felt like it discharged

A degraded original cell often had the watch automatically throttling always-on display and continuous heart rate polling to compensate for reduced capacity. With a fresh 350mAh cell at full impedance, the watch restores those features to full activity — so the new battery can appear to drain faster than the old one did in its final weeks. This is normal behaviour, not a cell defect. Check Samsung Wearable app settings and confirm always-on display and continuous HR monitoring are set to your preferred state rather than auto. Current draw will stabilise after the first few charge cycles as the fuel gauge IC locks in an accurate capacity baseline.

Watch not pairing to phone after battery replacement

Removing the battery kills the BLE session entirely — the watch loses its pairing state when power is cut at the cell level. The phone retains the old pairing record but the watch no longer recognises it, causing a connection loop on reassembly. Open the Galaxy Wearable app on your phone, select "Disconnect and unpair," then restart both devices. Initiate a fresh pairing from the watch's Bluetooth settings — do not use the phone's native Bluetooth menu, as Active 2 pairing must be initiated through the Wearable app to re-establish the full data link.