Telstra N600 Replacement Battery 3.7V 800mAh Li-ion

Telstra N600 / U260 / F100 — 3.7V Li-ion Replacement Battery (Li3710T42P3h553457)

This is a 3.7V, 800mAh Li-ion battery replacing part number Li3710T42P3h553457 across the Telstra N600 and its related variants. It fits the N600, U260, F100, C370, and over 46 additional models that share the same cell footprint and connector layout. Physical dimensions are 54.54 × 33.69 × 5.26mm — measure before installing if unsure of your exact variant.

• Multi-model fit across the N600 platform: The N600, U260, F100, and C370 share the same battery bay dimensions, connector pin-out, and 3.7V nominal voltage rail. The BMS communication handshake is identical across these variants, so one cell part number covers the full range.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the N600 platform. The BMS accepted the cell without fault flags, charge termination fired correctly at 4.2V, and the protection circuit tripped as expected on a simulated short.
• Fuel gauge recalibration on first install: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle before relying on the percentage indicator. This lets the fuel gauge IC map the new cell's discharge curve before drawing higher charge currents into an uncalibrated cell.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage-cliff problem, not a capacity problem. When the modem or display pulls a burst of current, the new cell's voltage dips below the BMS cutoff threshold momentarily — even if the fuel gauge still shows 25%. The OS reads a shutdown, not a low-battery event. Run one full discharge cycle down to automatic shutoff, then charge uninterrupted to 100% — this recalibrates the coulomb counter and shifts the perceived cliff to the correct low-voltage point near 3.4V per cell.

Phone warm near the battery compartment during first charge

A fresh cell has slightly higher internal impedance than a cycled one. The charge IC on the N600 maintains constant-current until the cell reaches 4.2V, and on a high-impedance cell that phase runs longer and generates more heat than normal. This is expected behaviour on cycle one and typically normalises by cycle three. If the phone feels hot to the touch rather than warm, pause charging and check that the charger output does not exceed 5V 1A — anything higher can stress an uncalibrated cell in that first constant-current window.