Technaxx C5000 Replacement Battery 3.7V 750mAh Li-ion

Technaxx C5000 — 3.7V Li-ion Replacement Battery

This is a 3.7V 750mAh Li-ion cell for the Technaxx C5000 smartphone. It fits directly in place of the original battery when the existing cell has degraded or failed completely. Capacity matches the factory specification at 750mAh (2.78Wh).

• C5000 cell fitment: The C5000 uses a compact 53.49 × 33.44 × 6.91mm cell with a 3.7V nominal rail. This replacement matches those physical and electrical parameters so the phone's charge IC communicates with the cell without flagging a mismatch.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a controlled rig. The BMS held the charge cutoff at 4.2V and the low-voltage cutoff triggered cleanly before cell damage could occur — no runaway, no unexpected disconnect mid-cycle.
• Fuel gauge recalibration on first install: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC build an accurate discharge curve against the new cell before high-current charging pushes current into an uncalibrated state.

Why the C5000 reports wrong battery percentage after a cell swap

The C5000's fuel gauge IC stores a learned discharge curve from the old cell. When a new cell goes in, that stored curve no longer matches actual cell behaviour. The OS reads voltage-based estimates against the old model, so percentages appear incorrect — often jumping or freezing at specific points. One full discharge-to-shutdown followed by a complete charge resets the coulomb counter and lets the IC build a fresh curve against the new cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell's internal resistance causes a voltage sag under load — typically when the modem fires or the screen brightness peaks — that drops the cell below the BMS cutoff threshold before the displayed percentage reaches zero. The fuel gauge IC hasn't yet mapped the new cell's voltage cliff, so it doesn't warn the OS in time. Let the phone shut down naturally from this point, then charge to 100% without interruption. After two or three full cycles the gauge IC recalibrates and the premature shutdowns stop.