About this replacement
Samsung Galaxy Watch 6 Classic 43mm — 3.88V Li-Polymer Replacement Battery (GH43-05160A)
This is a 3.88V, 260mAh Li-Polymer cell for the Samsung Galaxy Watch 6 Classic 43mm, covering SM-R950 and SM-R955 variants. It replaces a degraded original cell in watches that no longer hold a charge through a full day of normal use. OEM part numbers GH43-05160A and EB-BR955ABY both cross to this cell.
- SM-R950 and SM-R955 fitment: Both variants share the same battery bay dimensions, connector orientation, and BMS handshake protocol — the same 21.30 x 21.10 x 4.70mm cell fits either watch without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Watch 6 Classic unit. The BMS accepted the cell without fault codes, and the fuel gauge IC initialised correctly after a full charge from near-zero.
- Post-swap charge requirement: 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 loses its reference point during cell removal — it cannot recalibrate unless it completes a full charge cycle starting from near-zero. Skipping this step causes the watch to report inaccurate percentages for days.
Why the Watch 6 Classic reports wrong battery percentages after a cell swap
The Watch 6 Classic uses a fuel gauge IC that tracks charge state by counting coulombs from a known reference point. When you remove the old cell, that reference is wiped. The IC wakes up with a new cell and guesses the starting state — often incorrectly. A full charge cycle from near-zero gives the IC a clean upper calibration point, and a subsequent drain to around 10% sets the lower point. Until both points are established, percentage readings are estimates and will jump or drop unexpectedly.
Magnetic charger not making contact after reassembly
The Watch 6 Classic charges through a magnetic puck that aligns to contact pads on the watch case back. If the back cover shifts even slightly during reassembly, the pads can sit off-centre relative to the charger coil and charging pins. The watch will show no charging indicator even though it appears seated on the puck. Re-seat the case back, press firmly around the perimeter until it clicks flush, then place it on the charger and confirm the charging icon appears within 10 seconds.