KAZAM Trooper X5.0 KAX50 Compatible Battery 3.7V 2000mAh

KAZAM Trooper X5.0 — 3.7V Li-ion Replacement Battery (KAX50)

This is a 3.7V, 2000mAh Li-ion cell for the KAZAM Trooper X5.0 smartphone. It replaces the original KAX50 battery when the existing cell has lost capacity or stopped holding charge. Capacity is rated at 7.4Wh and matches the original cell's physical dimensions at 70.18 × 60.00 × 4.67 mm.

• Trooper X5.0 fitment: The X5.0 uses a removable 3.7V single-cell pack with the KAX50 part number. The connector pinout and BMS communication lines match the charge IC on the X5.0 motherboard, so the fuel gauge IC can read cell state correctly from the first boot.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench and monitored BMS handshake with the charge controller. The protection circuit responded correctly to cutoff thresholds at both ends of the voltage range.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-to-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before the coulomb counter locks in its reference points — skipping this step causes inaccurate percentage readings for the first several cycles.

Sudden shutdown at 20–30% on the Trooper X5.0

This is a voltage cliff failure. When an aged or degraded cell cannot sustain voltage under the combined load of the modem radio and screen backlight, the cell voltage drops sharply below the BMS cutoff threshold — even if the fuel gauge still shows charge remaining. The phone cuts out because the protection circuit sees a voltage below the safe floor, not because the mAh are exhausted. Replacing the cell resolves this if the fuel gauge IC is then recalibrated with one full discharge-charge cycle; the cutoff on a healthy new cell sits above 3.0V under load.

Phone showing incorrect battery percentage after cell swap

The Trooper X5.0's fuel gauge IC stores a learned discharge curve from the old cell. After a cell swap, that stored curve no longer matches the new cell's actual voltage-to-capacity relationship, so the percentage reading drifts — often jumping several points or freezing before correcting. The fix is a full recalibration cycle: charge to 100%, let the phone discharge fully until it shuts off, then charge back to 100% without interruption. After one complete cycle the coulomb counter resets its reference and percentage accuracy normalises.