About this replacement
Samsung Galaxy Watch Active — 3.85V Li-Polymer Replacement Battery (GH43-04922A)
This 3.85V, 230mAh Li-Polymer cell replaces the original battery in the Samsung Galaxy Watch Active (SM-R500, SM-R500N). It fits the same physical footprint as the OEM cell at 22.40 × 20.50 × 5.00mm and connects to the same flex connector on the watch mainboard. Swap it when the original cell no longer holds a full charge or shuts down unexpectedly under load.
- SM-R500 and SM-R500N compatibility: Both watch variants share the same battery bay dimensions, flex connector pinout, and BMS handshake protocol — the fuel gauge IC on the mainboard communicates over the same lines regardless of regional SKU.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on an SM-R500 unit, confirming the BMS accepted the cell without fault flags, the fuel gauge initialised correctly after a full charge cycle, and the watch resumed normal sensor operation.
- Post-swap charging protocol: After fitting this cell, place the watch on its magnetic charger immediately and charge to 100% before first use. The fuel gauge IC on the Galaxy Watch Active cannot calibrate its state-of-charge reference without a full charge cycle from near-zero after a cell swap — skipping this step causes the percentage readout to drift or report 0% incorrectly.
Why the Galaxy Watch Active reports incorrect battery percentage after a cell swap
The SM-R500 uses a coulomb-counting fuel gauge IC that tracks charge by measuring current flow over time. When the old cell is removed, the IC loses its accumulated reference data entirely. The new cell arrives with a partial charge state the IC has never measured, so the displayed percentage is a guess at best. A single full charge cycle — from near-zero to 100% on the magnetic charger — resets and rebuilds the IC's reference, giving accurate readings from that point forward.
Watch draining to empty in under a day after battery replacement
If the watch drops to 0% within a single day after fitting this cell, check whether always-on display and continuous heart rate monitoring are both active — that combination sustains a near-constant sensor and display draw on a 230mAh cell. The heart rate sensor on a freshly swapped cell can also draw slightly higher current for the first several charge cycles while operating against the new cell's impedance profile. Disable always-on display temporarily, complete three full charge cycles, then re-enable it and monitor drain. If it still drops inside a day with both features off, reseat the flex connector at 3.85V nominal and confirm it is fully latched.