Orange San Francisco Li3713T42P3h444865 3.7V 1300mAh Replacement Battery

Orange San Francisco / P729B — 3.7V Li-ion Replacement Battery (Li3713T42P3h444865)

This is a 3.7V 1300mAh Li-ion replacement battery for the Orange San Francisco and P729B smartphones. It slots directly into the original battery bay and connects to the same charge IC and fuel gauge circuit. Capacity is rated at 1300mAh (4.81Wh), matching the original factory specification.

• San Francisco and P729B compatibility: Both devices share the same ZTE-sourced motherboard, voltage rail, and BMS handshake protocol. The cell dimensions — 43.50 × 47.00 × 6.10mm — and OEM part numbers Li3713T42P3h444865 and Li3712T42P3h444865 cover both variants without modification.
• Bench tested on actual hardware: We ran charge and discharge cycles on the San Francisco with this cell installed. The BMS accepted the new cell on first connection, charge termination triggered correctly at 4.2V, and the protection circuit tripped as expected at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-to-charge cycle without interruption. This lets the fuel gauge IC map the new cell's discharge curve before reporting percentage to the OS — skipping this step causes erratic or inaccurate percentage readings for the first several days.

Sudden shutdown at 20–30% on the Orange San Francisco after a cell swap

The San Francisco's fuel gauge IC retains the old cell's voltage-to-capacity curve in memory after a swap. A fresh cell has a slightly different discharge profile, so the gauge misjudges how much usable capacity remains. When the modem or screen draws current at what the OS thinks is 25%, the actual cell voltage can drop below the protection threshold instantly. The fix is one full uninterrupted discharge cycle down to auto-shutdown, then a full charge — this forces the coulomb counter to resync against real cell data.

Orange San Francisco won't power on after sitting in storage with a flat battery

Li-ion cells that self-discharge below approximately 2.5V trigger a BMS lockout — the protection circuit opens and blocks current flow to prevent further cell damage. The phone shows nothing when you press the power button, and plugging in a charger produces no response. Connect the phone to a low-current USB charger (500mA wall adapter, not a fast charger) and leave it for 20–30 minutes without pressing anything. Once the cell climbs above the BMS recovery threshold — typically around 2.9–3.0V — the protection circuit re-closes and normal charging resumes.