About this replacement
Samsung Gear Fit 2 Pro / SM-R365 — 3.85V Li-Polymer Replacement Battery (EB-BR365ABE)
This is a 3.85V, 200mAh lithium-polymer cell (EB-BR365ABE / GH43-04770A) for the Samsung Gear Fit 2 Pro smartwatch, model SM-R365. It powers the display, heart rate sensor, GPS, and fitness tracking functions. Replace it when the original cell no longer holds a charge or the watch fails to power on.
- Gear Fit 2 Pro / SM-R365 fitment: Both part numbers (EB-BR365ABE and GH43-04770A) refer to the same Samsung-spec cell. The SM-R365 uses a 3.85V nominal rail with a flat Li-Polymer form factor measuring 30.00 × 15.50 × 6.00mm — the connector and BMS handshake match this cell directly.
- Bench tested on actual hardware: We cycled this cell through the SM-R365 charge circuit and confirmed the BMS accepted the cell without error flags. Charge current tapered correctly at full capacity, and the fuel gauge IC registered a valid state-of-charge reading after one complete cycle.
- Post-swap charge routine for the SM-R365: Place the watch on its magnetic charger immediately after fitting this cell and charge it to 100% before first use. The fuel gauge IC on this platform loses its reference point when the cell is removed — it cannot recalibrate without a full charge cycle starting from near-zero.
Watch showing 0% immediately after battery swap
The SM-R365 uses a coulomb-counting fuel gauge IC that tracks charge state relative to a stored reference. When the cell is removed, that reference resets to zero. The watch reads 0% not because the new cell is flat, but because the IC has no baseline to work from. Put the watch straight on the charger and let it run to 100% — once the IC completes that first full cycle, percentage readings return to normal.
Heart rate sensor running the new cell flat in under a day
Continuous heart rate monitoring on the Gear Fit 2 Pro keeps the optical sensor active at all times, which accounts for a significant share of total draw on a 200mAh cell. If the watch is also set to always-on display, combined draw can exhaust the cell well before the expected multi-day window. Switch heart rate monitoring to "every 10 minutes" in the Samsung Health app and disable always-on display — these two changes are the single biggest factor in extending charge intervals on this platform.