KAZAM Trooper X4.0 Replacement Battery KAX10 3.7V 1600mAh

KAZAM Trooper X4.0 — 3.7V Li-ion Replacement Battery (KAX10)

This is a 3.7V, 1600mAh Li-ion cell that directly replaces the original battery in the KAZAM Trooper X4.0 smartphone. It fits the Trooper X4.0 only — confirm your model before ordering. Capacity figures come from the product data, not estimates.

• Trooper X4.0 fit: The X4.0 uses a fixed connector pinout and a BMS that checks cell voltage at boot. This cell matches that voltage rail and connector layout, so the BMS handshake completes on first power-on without triggering a low-voltage lockout.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the bench. The BMS accepted charge current without fault flags, and the protection circuit triggered correctly at the low-voltage cutoff threshold.
• First-cycle fuel gauge reset: On first use after installation, disable fast charging and run one complete discharge-charge cycle. The Trooper X4.0's fuel gauge IC was calibrated to the old cell's discharge curve — one full cycle gives it new reference points before any high-current charge session begins.

Sudden shutdown at 20–30% on the Trooper X4.0 after a cell swap

This happens because the fuel gauge IC still holds the discharge curve of the old, degraded cell. When the new cell hits a voltage point the IC maps to "20% remaining," the actual cell voltage under modem or screen load drops faster than the old curve predicted. The phone interprets this as a voltage cliff and shuts down to protect the hardware. One full discharge-charge cycle — draining to auto-off and charging uninterrupted to 100% — rewrites the IC's reference curve to match the new cell.

Phone won't power on after sitting in storage with a flat battery

Li-ion cells stored fully discharged can drop below 2.5V per cell, which trips the BMS into a deep-discharge lockout — a hard protection state that blocks normal boot. Plugging in a charger may show nothing on screen for up to 15 minutes while the charge IC trickle-feeds current to bring the cell back above the BMS re-entry threshold. If the screen remains black, confirm the charger is delivering at least 5V at 500mA and leave it connected for a full 20 minutes before attempting a power-on.