GSmart S1200 Replacement Battery GPS-H03 3.7V 1010mAh

GSmart S1200 Series — 3.7V Li-ion Replacement Battery (GPS-H03)

This is a 3.7V, 1010mAh Li-ion battery for the GSmart S1200, S1205, and S1208 smartphones. It replaces OEM part GPS-H03 (also cross-referenced as 29S00-060F0-S90S). Swap it in when the original cell no longer holds charge or shuts the phone down unexpectedly.

• S1200 / S1205 / S1208 fit: All three models share the same battery bay dimensions, connector pinout, and BMS handshake protocol — one cell covers the entire S1200 platform without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and load discharge on the S1200 platform. The BMS accepted the cell without a protection trip, and the charge IC brought it to 4.2V without thermal events.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated state.

Sudden shutdown at 20–30% on the S1200 after a cell swap

The S1200's fuel gauge IC retains the discharge curve from the original cell in its coulomb counter. When a new cell is installed, the stored curve no longer matches actual cell voltage under load — especially during modem transmit bursts or screen-on peaks. The phone reads 25% remaining but the cell voltage drops below the BMS cutoff threshold under that sudden current draw. One full discharge cycle from 100% to automatic shutdown, followed by a full charge, resets the coulomb counter to the new cell's actual curve.

Phone will not power on after the replacement battery sat in storage

Li-ion cells self-discharge in storage, and the BMS on this cell will enter lockout if voltage drops below approximately 2.5V per cell during extended shelf time. The phone shows nothing — no boot screen, no charging indicator. Connect the phone to a wall charger (not a USB port) and leave it for 20–30 minutes without attempting to power it on. Once the BMS detects sufficient voltage recovery, the charge IC re-engages and the phone will show the charging animation. If no response after 45 minutes, confirm the charger is delivering at least 5V.