Prunus L-288 Replacement Battery 3.7V 1200mAh Li-ion

Prunus L-288 — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1200mAh Li-ion cell for the Prunus L-288 mobile phone. It fits the L-288 directly, restoring power when the original cell has degraded or failed. Capacity is 4.44Wh — matched to the original specification.

• L-288 cell compatibility: The L-288 uses a compact single-cell pack at 3.7V nominal. The physical footprint is 53.00 × 33.90 × 5.70mm — any deviation will prevent the rear cover from seating or cause connector misalignment. This cell matches all three dimensions.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench. The BMS accepted charge handshake correctly, held voltage above 3.6V through mid-discharge, and tripped protection at the expected low-voltage threshold without false cutoffs.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-to-charge cycle before resuming normal use. The phone's fuel gauge IC was calibrated to the old cell's discharge curve — one full cycle lets it remap to the new cell before high-current charging begins.

Sudden shutdown at 20–30% on the Prunus L-288 after a cell swap

This is a voltage cliff issue, not a capacity problem. A fresh cell has a slightly different discharge curve than the degraded original — the fuel gauge IC still uses the old curve to estimate state of charge. When the phone reports 25%, the new cell may already be at 3.5V or lower under modem and screen load, which crosses the BMS cutoff threshold. The phone shuts off before the display reaches 0%. One full discharge-charge cycle forces the coulomb counter to re-anchor its curve to the new cell, and the shutdowns stop.

Battery percentage jumping erratically after replacement

Erratic percentage readings — jumping from 60% to 80% or dropping suddenly — point to a fuel gauge IC that has not yet mapped the new cell. The IC uses stored charge-curve data from the old, degraded cell to estimate remaining capacity, and the mismatch produces unstable readings. This is not a fault with the replacement cell itself. Drain the phone fully until it shuts down automatically, charge uninterrupted to 100%, and the gauge will stabilise from that point forward.