Alcatel OT-665 Replacement Battery CAB22D0000C1 3.7V 700mAh

Alcatel OT-665 / OT-356 Series — 3.7V Li-ion Replacement Battery (CAB22D0000C1)

This is a 3.7V 700mAh Li-ion cell for the Alcatel OT-665, OT-665X, One Touch 665, OT-356, and 18 additional compatible models. It slots into the original battery bay and connects to the same charge management circuit these phones shipped with. Dimensions are 46.60 × 33.90 × 4.60mm — confirm yours before ordering.

• OT-665 and OT-356 series compatibility: These models share the same 3.7V single-cell architecture, connector pinout, and charge IC handshake. One cell covers the full range without modification.
• Bench tested on actual hardware: We cycled this cell through the OT-665 charge circuit and monitored BMS cutoff behaviour at both ends of the voltage window. The protection circuit tripped correctly at 4.2V charge termination and held the low-voltage cutoff at 3.0V under load.
• Fuel gauge recalibration on first use: On first use after installation, run one full discharge to automatic shutdown followed by an uninterrupted charge to 100%. This gives the fuel gauge IC one complete reference cycle against the new cell's actual discharge curve before the OS starts reporting percentage to the screen.

Why the OT-665 reports the wrong battery percentage after a cell swap

The OT-665 uses a fuel gauge IC that builds its percentage model from learned discharge data on the previous cell. When you swap in a new cell, the IC still references the old cell's internal resistance and voltage-to-capacity curve. The result is percentage readings that are either inflated early in discharge or that drop suddenly in the lower range. One full uninterrupted discharge-to-shutdown and recharge cycle resets the learned curve to the new cell. After that cycle, percentage accuracy returns to normal.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff problem, not a capacity problem. Under load — backlight on, active call, or radio scan — the cell's terminal voltage drops faster than the fuel gauge's stored curve predicts. The phone's protection circuit sees voltage fall below the safe threshold and cuts power before the reported percentage reaches zero. It is most common in the first few cycles on a new cell, when the fuel gauge IC is still working from the old cell's data. Complete two full discharge-recharge cycles and the reported percentage at shutdown will stabilise closer to 5–10%.