Alcatel OT-500 Compatible Battery 3.7V 900mAh Li-ion

Alcatel OT-500 / OT-501 / OT-700 / OT-701 Series — 3.7V Li-ion Replacement Battery

This is a 3.7V 900mAh Li-ion cell for the Alcatel OT-500, OT-501, OT-700, OT-701, and eight additional OT-series models that share the same battery bay and connector. It replaces the original cell when the phone no longer holds a usable charge through a normal day. Capacity is 900mAh (3.33Wh) — matching the factory specification.

• OT-500 and OT-700 platform compatibility: These models share a common battery footprint, connector pinout, and charge IC handshake across both the 500 and 700 sub-families. The cell slots into all listed variants without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on OT-series hardware. The BMS accepted the charge IC handshake cleanly, held voltage above 3.5V under normal call and screen load, and hit the low-voltage cutoff without tripping an early protection event.
• Fuel gauge recalibration on first use: After fitting this cell, run one full discharge to automatic shutdown, then charge uninterrupted to 100% before normal use. The OT-series fuel gauge IC references the old cell's discharge curve — one complete cycle overwrites it with the new cell's profile.

Why the OT-500 reports wrong battery percentage after a cell swap

The OT-series uses a simple coulomb-counting fuel gauge that calibrates against the specific discharge curve of the installed cell. When you fit a new cell, the gauge still references the previous cell's learned curve. This mismatch causes the percentage to read high, then drop suddenly — not because the cell is faulty, but because the gauge has no valid reference data yet. One full discharge-to-cutoff followed by a complete uninterrupted charge resets the reference and restores accurate reporting.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops sharply under the load of an active call or backlight — a voltage cliff that the gauge reads as 20–30% remaining but the BMS reads as a protection threshold breach. On a new cell that hasn't been calibrated, the fuel gauge cannot predict this cliff accurately. The fix is the same full-cycle calibration: discharge completely to auto-shutdown, then charge to 100%. After that cycle, the gauge knows where the voltage cliff sits and the OS percentage will track it correctly, stopping the unexpected cutoff.