Ticwatch C2 Smartwatch Replacement Battery 3.85V 400mAh

Ticwatch C2 — 3.85V Li-Polymer Replacement Battery (SP502626SF)

This is a 3.85V, 400mAh Li-Polymer cell that replaces the original SP502626SF battery in the Ticwatch C2 smartwatch. It restores full operation across timekeeping, heart rate monitoring, activity tracking, and smart notifications. Dimensions are 25.80 x 24.00 x 5.10mm — confirm these against your existing cell before fitting.

• Ticwatch C2 fitment: The C2 uses a compact pouch cell with a low-profile connector matched to the watch's mainboard. Voltage tolerance on this platform is tight — the BMS expects a 3.85V nominal cell to correctly report state-of-charge through the fuel gauge IC. Substituting a mismatched voltage causes inaccurate percentage readings and premature cutoff.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the C2 mainboard. The BMS accepted the cell without fault flags, the fuel gauge IC initialised correctly after a full charge cycle, and the connector seated without play at the board-side socket.
• Post-swap charging protocol: Place the watch on its magnetic charger immediately after fitting the new cell and charge it to 100% before first use. The fuel gauge IC on the C2 cannot calibrate its reference point without a complete charge cycle from near-zero following a cell swap — skipping this step causes the percentage display to read incorrectly from the start.

Why the Ticwatch C2 shows 0% and won't boot after a battery swap

The C2 uses a coulomb-counting fuel gauge IC that tracks charge by measuring current flow in and out of the cell. When the cell is physically removed, that reference is lost entirely. The IC boots with no data and defaults to 0%, and the BMS may refuse to allow boot until it sees a valid voltage window. Placing the watch straight onto the charger after fitting the new cell allows the IC to re-establish its reference — the watch will typically power on within a few minutes of charging.

Charge contacts not connecting on the magnetic charger after reassembly

If the watch back is not seated flush after reassembly, the magnetic charging contacts on the case can shift by fractions of a millimetre — enough to break the circuit with the charger puck. The watch will show no charging animation and the battery will not recover. Press the back cover down firmly and uniformly before attempting to charge. Confirm the charger is making contact by checking for the charging indicator within 10 seconds of placing the watch on the puck.