ESIA Qwerty Mini 3.7V 880mAh Replacement Battery Li-ion

ESIA Qwerty Mini — 3.7V Li-ion Replacement Battery

This is a 3.7V Li-ion cell rated at 880mAh (3.26Wh), built to fit the ESIA Qwerty Mini compact smartphone. It replaces the original cell when capacity has degraded or the battery no longer holds a usable charge. Dimensions are 44.00 × 38.00 × 5.20mm — verify these against your existing cell before fitting.

• Qwerty Mini fit: The Qwerty Mini uses a removable battery bay with a fixed contact layout. This cell matches that footprint and connector alignment. No OEM part number was published for this model, so physical dimensions are the primary compatibility check.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench, monitoring BMS cutoff thresholds at both ends. The protection circuit held low-voltage cutoff correctly and accepted a full charge without thermal event.
• Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard rate. The fuel gauge IC on the Qwerty Mini is calibrated to the original cell's discharge curve — a full slow cycle lets it map the new cell before normal charging resumes.

Sudden shutdown at 20–30% on the replacement cell

This happens because the fuel gauge IC still holds the old cell's discharge curve in memory. When the new cell hits a voltage point the gauge hasn't mapped yet, the phone sees an unexpected voltage drop under screen or modem load and triggers a protective shutdown. The percentage shown is wrong — the cell is actually closer to empty than the OS thinks. One full discharge-charge cycle at standard rate forces the coulomb counter to rebuild its curve against the new cell. After that cycle, shutdowns at 20–30% typically stop.

Phone won't power on after the replacement cell sat in storage

Li-ion cells self-discharge during storage. If this cell dropped below 2.5V per cell while sitting unused, the BMS enters a lockout state and blocks normal charge current to prevent damage to a deeply discharged cell. The phone shows nothing when you press the power button — no logo, no charging indicator. Connect to a charger and leave it for 15–20 minutes without pressing anything; most BMS circuits on this cell class use a trickle pre-charge mode that slowly brings voltage above the lockout threshold before allowing full charge current. If the screen shows a charging indicator after that wait, the BMS has recovered — continue charging to 100% before first use.