TCL E330 Replacement Battery 3.7V 800mAh Li-ion

TCL E330 / T36 — 3.7V Li-ion Replacement Battery

This is a 3.7V, 800mAh Li-ion cell for the TCL E330 and T36 mobile phones. It slots in where the original battery sits and restores power to the device. Capacity is rated at 800mAh (2.96Wh) — matching the original specification.

• E330 and T36 shared platform: Both handsets run the same voltage rail and use the same physical cell footprint — 49.34 x 40.00 x 4.45mm. The connector and BMS contact layout are identical across both models, so one cell covers both.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench. The BMS held charge termination correctly and showed no false-positive cutoff during load testing. Cell voltage at rest settled to the expected 3.7V nominal.
• Fuel gauge recalibration on first use: On first installation, run one full discharge to near-empty and then a full uninterrupted charge before relying on the percentage readout. This gives the fuel gauge IC a complete reference curve for the new cell — skip it and the percentage display will be inaccurate for the first several cycles.

Sudden shutdown at 20–30% on the replacement cell

A new cell does not automatically inherit the old fuel gauge calibration stored in the phone's coulomb counter. When the counter expects the old degraded cell's discharge curve, it misreads how much charge remains. Under load — screen backlight plus radio transmit — voltage can drop faster than the counter predicts, and the phone shuts off to protect the cell even though the display showed 20–30% remaining. One full discharge-charge cycle recalibrates the counter against the actual curve of the new cell. After that cycle, the shutdowns stop.

Phone will not power on after the battery has been sitting uncharged

If a replacement cell has been stored for several months or the phone was left discharged, the cell voltage can fall below 2.5V. The BMS enters a lockout state at that threshold and will not pass current to the phone even when a charger is connected. Connect the phone to a low-current USB charger — 5V/500mA is enough — and leave it for 20–30 minutes without attempting to power it on. This trickle phase brings the cell back above the BMS unlock threshold, typically around 3.0V, after which normal charging resumes.