Telstra G380 Replacement Battery Li3713T42P3h614057 3.7V 1200mAh

Telstra G380 — 3.7V Li-ion Replacement Battery (Li3713T42P3h614057)

This is a 3.7V, 1200mAh Li-ion cell that replaces the factory battery in the Telstra G380, J-G380, F165, and F165i smartphones. The OEM part number is Li3713T42P3h614057. When the original cell degrades and the phone can no longer hold a charge through a normal day, this battery slots in as a direct replacement.

• G380 and F165 series compatibility: The G380, J-G380, F165, and F165i all run the same 3.7V battery rail and share the same physical connector and cell footprint — 61.48 × 39.94 × 5.44mm — so one part number covers the entire family without BMS handshake conflicts.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the G380 platform. The BMS accepted the cell without error flags, and the protection circuit tripped correctly at low-voltage cutoff — no false trips under screen-on or call load.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging begins. Skipping this step is the primary cause of erratic percentage jumps in the first few days after a swap.

Sudden shutdown at 20–30% on the G380 after a cell swap

A new Li-ion cell has a slightly different voltage-versus-capacity curve than the worn cell the fuel gauge IC was trained on. When the modem fires or the screen brightness spikes, current draw causes a brief voltage sag. If the IC reads that sag as a low-voltage cutoff event, the phone shuts down even though the cell still has charge remaining. This is not a faulty battery — it is the fuel gauge IC working off a stale calibration curve. Run one full discharge to 1–2% followed by a full uninterrupted charge to 100% with fast charging off. After that cycle the IC recalibrates and the premature shutdowns stop.

Phone warm near the battery compartment during the first few charges

A fresh cell arrives with elevated internal impedance compared to a cell that has been broken in. The charge IC on the G380 pushes current into that higher-impedance cell, and the increased resistance generates more heat than normal during the first two or three charge cycles. This is expected behaviour and typically resolves by the third full charge as the cell's impedance settles. If the phone remains noticeably warm past the third cycle, check that the battery contacts are seated flat — a partially seated cell increases contact resistance and compounds the heat issue.