Technaxx C5000 Replacement Battery 3.7V 1000mAh Li-ion

Technaxx C5000 — 3.7V Li-ion 1000mAh Replacement Battery

This is a 3.7V Li-ion cell rated at 1000mAh (3.7Wh), built as a direct swap for the Technaxx C5000 smartphone. It matches the original cell footprint at 52.95 × 33.07 × 8.01mm, so it seats cleanly in the battery bay. If your C5000 no longer holds a charge through a normal day, this cell replaces the degraded original.

• C5000 battery bay fit: The C5000 uses a slim single-cell Li-ion configuration at 3.7V nominal. This replacement matches that voltage rail exactly, keeping the charge IC and fuel gauge IC operating within their expected input range without any adapter or connector modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench, monitoring BMS cutoff behaviour at both ends of the voltage window. The protection circuit triggered correctly at the low-voltage threshold and did not trip under normal charge-current conditions.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging if your C5000 supports it, and run one full discharge-to-charge cycle before resuming normal use. This lets the fuel gauge IC build an accurate discharge curve against the new cell, preventing erratic percentage readings from the first session onward.

Why the C5000 reports wrong battery percentage after a cell swap

The C5000 fuel gauge IC uses a coulomb counter that was calibrated to the discharge curve of the original cell. When a new cell goes in, that stored curve no longer matches the actual cell behaviour, so the reported percentage drifts. The gauge may show 40% but the cell voltage is already near the low-voltage cutoff. One complete discharge from 100% down to automatic shutdown, followed by a full uninterrupted charge, forces the IC to rewrite its reference curve against the new cell. After that cycle, percentage readings stabilise.

Sudden shutdown at 20–30% on the C5000 after replacement

This happens when the modem or display pulls a short burst of current the cell cannot sustain at that state of charge, causing voltage to sag below the BMS cutoff threshold even though the gauge still shows charge remaining. It is most common in the first few cycles before the fuel gauge IC recalibrates. The phone shuts off to protect the cell, not because the cell is faulty. Run two full discharge-charge cycles and confirm cell voltage reads above 3.6V at the point where shutdown previously occurred.