KAZAM Life B4 Replacement Battery KAB4 3.7V 800mAh

KAZAM Life B4 — 3.7V Li-ion Replacement Battery (KAB4)

This is a 3.7V, 800mAh Li-ion battery for the KAZAM Life B4 smartphone. It replaces the original KAB4 cell when the existing battery no longer holds adequate charge for calls, messaging, or basic Android use. Capacity is 800mAh — identical to the factory specification.

• KAZAM Life B4 fit: The Life B4 uses a single-cell 3.7V Li-ion pack with a low pin-count connector and a basic BMS that handles overcharge and over-discharge cutoff. This cell matches that voltage rail, physical footprint (66.60 × 33.90 × 4.50mm), and connector pinout exactly.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a Life B4 unit. The BMS accepted the charge handshake on first connection, overcharge cutoff triggered correctly at 4.2V, and the over-discharge cutoff held at the expected low-voltage threshold.
• Fuel gauge recalibration on first cycle: After fitting this cell, run one full discharge to around 5–10% and then a complete charge to 100% before relying on the percentage reading. The fuel gauge IC in the Life B4 is calibrated to the old cell's discharge curve and needs one full cycle against the new cell to reset its coulomb counter.

Why the Life B4 reports wrong battery percentage after a cell swap

The Life B4's fuel gauge IC builds its capacity model from the discharge curve of the cell it learned on. When a new cell goes in, that learned curve no longer matches the actual cell chemistry and impedance. The result is a percentage reading that drifts — sometimes showing 40% and cutting off, or jumping from 30% to 15% in seconds. One full discharge-to-charge cycle forces the coulomb counter to rebuild its baseline against the new cell. After that cycle, percentage accuracy returns to normal.

Sudden shutdown at 20–30% on the Life B4 after fitting a replacement

This shutdown pattern is a voltage cliff, not a capacity fault. When the modem fires up for a call or the screen brightness spikes, instantaneous current draw pulls cell voltage down sharply. If the fuel gauge IC has not yet recalibrated, it allows discharge past the point where the cell can sustain that load — and the BMS cuts output to protect the cell. The phone powers back on immediately because resting voltage recovers above the BMS threshold. Run one complete discharge-charge cycle to recalibrate the fuel gauge, and confirm the BMS low-voltage cutoff is triggering below 3.0V per cell.