Alcatel K132 Replacement Battery 3.7V 750mAh Li-ion

Alcatel K132 / OT-S850 — 3.7V Li-ion Replacement Battery

This is a 3.7V, 750mAh Li-ion replacement battery for the Alcatel K132 and OT-S850 mobile phones. It slots directly into either handset and restores normal call, messaging, and standby functions. Capacity figure is 750mAh (2.78Wh) — matching the original cell specification.

• K132 and OT-S850 compatibility: Both models share the same 3.7V single-cell Li-ion architecture, connector pinout, and BMS handshake protocol — one cell fits both without modification.
• Bench tested on actual hardware: We cycled this cell through charge and load on the K132 platform. The BMS accepted the cell without fault codes, and the charge IC reached full termination correctly on the first cycle.
• Fuel gauge recalibration on first use: On first installation, run one full discharge down to auto-shutoff, then charge uninterrupted to 100% before normal use. This lets the fuel gauge IC map the new cell's discharge curve accurately — skipping this step causes the percentage counter to read against the old cell's data.

Why the K132 reports wrong battery percentage after a cell swap

The K132 uses a fuel gauge IC that tracks capacity by measuring coulombs in and out against a stored discharge curve. That curve was built around the original cell's internal resistance and voltage profile. A new cell has a different impedance, so the stored curve no longer matches real voltage behaviour. One full discharge-to-shutoff followed by a complete charge forces the IC to rewrite its reference data against the new cell.

Sudden shutdown at 20–30% remaining on the K132

This happens when the cell voltage drops sharply under load — typically during a call, when the modem radio draws a burst of current. At that moment, cell voltage can fall below the 3.2V BMS cutoff threshold even though the percentage counter still shows charge remaining. The fuel gauge hasn't recalibrated yet, so it reports an inflated state of charge right up to the cutoff. Fix: complete one full supervised discharge-charge cycle so the gauge IC anchors the empty point at the correct voltage floor.