KAZAM Trooper 441L Replacement Battery 3.7V 1500mAh TR4L401

KAZAM Trooper 441L / 440L — 3.7V Li-ion Replacement Battery (TR4L401)

This 3.7V, 1500mAh (5.55Wh) lithium-ion cell replaces the original battery in the KAZAM Trooper 441L and Trooper 440L smartphones. It matches OEM part numbers TR4L401 and TR4L40, fitting the same battery bay without modification. Dimensions are 58.25 × 46.10 × 5.00mm — verify these against your existing cell before installing.

• Trooper 441L and 440L compatibility: Both models share the same battery bay geometry, voltage rail, and connector pinout. The TR4L401 and TR4L40 part numbers reference the same physical cell across this short model run, so one replacement covers both variants.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench. The BMS accepted a full charge without tripping overcurrent protection, and voltage held stable under simulated screen and modem load across multiple cycles.
• Fuel gauge recalibration after swap: On first use after installation, run one complete discharge down to automatic shutoff, then charge uninterrupted to 100% before using the phone normally. This gives the fuel gauge IC a full reference cycle against the new cell's discharge curve before it starts reporting percentages to the OS.

Why the Trooper 441L reports wrong battery percentage after a cell swap

The Trooper 441L uses a fuel gauge IC that builds its percentage model from the learned discharge curve of the cell it was calibrated against. When a new cell goes in, that learned curve no longer matches the actual cell chemistry and internal resistance. The IC keeps referencing the old data, so it can report 40% remaining when the cell is physically closer to 15%. One full discharge-to-shutoff followed by a complete uninterrupted charge resets the coulomb counter reference and brings percentage reporting back in line with real capacity.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem or display draws a current spike that the cell cannot sustain at its present state of charge. Voltage dips below the BMS cutoff threshold — typically around 3.0V — and the phone shuts off even though the fuel gauge still shows charge remaining. It is more common in the first few cycles on a replacement cell, before the gauge IC has recalibrated. Run two full discharge-charge cycles without interruption and check whether shutdowns persist; if the cell voltage is holding above 3.2V under load by cycle three, the gauge is recalibrating correctly.