About this replacement
Samsung Galaxy Watch 5 Pro 45mm — 3.88V Li-Polymer Replacement Battery (EB-BR925ABY)
This 3.88V, 570mAh Li-Polymer cell is a direct replacement for the original battery in the Samsung Galaxy Watch 5 Pro 45mm (SM-R920, SM-R925). It powers the display, heart rate and sleep sensors, GPS, and Bluetooth connectivity. Fit it when the original cell no longer holds charge through a standard day of use.
- SM-R920 and SM-R925 compatibility: Both variants of the Watch 5 Pro share the same 27.80 × 25.00 × 6.80mm cell pocket, the same flex connector, and the same BMS handshake protocol. One replacement SKU covers both.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the SM-R925 platform. The BMS accepted the new cell without a firmware flag, and the fuel gauge registered charge state correctly after a full charge cycle post-swap.
- 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 Wear OS platforms loses its voltage reference when the cell is disconnected. Without a full charge cycle from near-zero, the percentage readout will be inaccurate and the watch may shut off unexpectedly at reported non-zero charge levels.
Why the Watch 5 Pro battery percentage jumps or drops sharply after a cell swap
The Watch 5 Pro uses a coulomb-counting fuel gauge that builds its state-of-charge model over charge and discharge cycles. When the old cell is removed, that learned model is erased. The IC starts recalculating from scratch using the new cell's impedance, which differs from the aged original. Until two or three full charge cycles complete, the reported percentage can jump by 10–20% or drop suddenly without warning. This settles after the gauge recalibrates.
Watch 5 Pro not pairing with phone after battery replacement
Removing power during a cell swap terminates the active BLE session between the watch and the paired phone. The Galaxy Wearable app holds the last session key, but the watch generates a new one on cold boot after a full power loss. Open the Galaxy Wearable app on the phone, select the watch, choose "Unpair," then re-initiate pairing from the watch's Bluetooth settings. The process takes under two minutes and restores all notification and health data sync.