Tizi EQ20644 Replacement Battery 3.7V 1050mAh Li-ion

Tizi EQ20644 — 3.7V Li-ion 1050mAh Replacement Battery

This is a 3.7V Li-ion cell rated at 1050mAh (3.89Wh), built to fit the Tizi EQ20644 smartphone. It replaces the original cell when capacity has dropped and the phone no longer holds a usable charge. Physical dimensions are 53.00 × 33.90 × 5.60mm — verify these against your original cell before installing.

• EQ20644 fit confirmation: The EQ20644 runs a standard 3.7V single-cell architecture. This replacement matches the voltage rail and connector pinout required by that platform. No adapter or modification is needed.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench and monitored BMS behaviour throughout. The protection circuit responded correctly at both low-voltage cutoff and charge termination — no false trips observed.
• Fuel gauge recalibration on first install: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard rate. This lets the fuel gauge IC map its coulomb counter against the new cell's discharge curve before any high-current session pushes charge into an uncalibrated state.

Sudden shutdown at 20–30% on the EQ20644 after a cell swap

This is a voltage cliff issue, not a capacity defect. When the modem transmits or the screen peaks in brightness, current draw spikes sharply. An uncalibrated fuel gauge IC reads the resulting voltage sag as a hard cutoff and shuts the phone down — even though percentage still shows 20–30%. Running one full discharge cycle to 0% and a full charge back to 100% at standard rate recalibrates the coulomb counter. After that cycle, the reported percentage tracks actual cell state accurately under load.

EQ20644 not powering on after the replacement cell sat in storage

Li-ion cells self-discharge during storage. If the cell dropped below approximately 2.5V, the BMS enters a lockout state and blocks normal charging to prevent damage to an over-discharged cell. The phone will not respond to a standard charger in this state. Connect the device to a charger and leave it undisturbed for 15–30 minutes — most charge ICs will trickle current into the cell at a reduced rate to bring voltage back above the BMS recovery threshold, typically around 2.9–3.0V, before resuming normal charge.