Bea-fon SL140 Replacement Battery 3.7V 1200mAh Li-ion

Bea-fon SL140 / SL240 / SL360 — 3.7V Li-ion Replacement Battery (SL140/SL240)

This is a 3.7V, 1200mAh Li-ion cell built to replace the original battery in the Bea-fon SL140, SL240, and SL360 mobile phones. It matches the OEM dimensions of 62.18 × 38.14 × 4.50mm, so it seats correctly in the battery bay without modification. Voltage and capacity spec come from the product data, not third-party estimates.

• SL140, SL240, SL360 compatibility: These three models share the same battery bay geometry, connector pinout, and BMS communication protocol — which is why a single cell covers all three. Swapping between them does not require a different SKU.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the SL140 platform. The BMS accepted charge input without fault flags, and cell voltage held above the low-voltage cutoff threshold throughout the discharge curve.
• Fuel gauge recalibration on first use: After fitting this cell, disable fast charging and run one complete discharge-to-charge cycle before normal use. The phone's fuel gauge IC was calibrated to the old cell's discharge curve — one full cycle lets it map the new cell accurately before high-current charging begins.

Sudden shutdown at 20–30% on the Bea-fon SL140 after a cell swap

The SL140 shuts down mid-use at 20–30% because the fuel gauge IC still holds the discharge curve of the old, degraded cell. The new cell has a steeper voltage drop under modem and screen load than the IC expects, so it misreads remaining charge and lets voltage collapse before triggering a clean shutdown. Run one full discharge from 100% to automatic shutdown, then charge uninterrupted to 100%. After that single cycle, the coulomb counter resets against the new cell and percentage readings stabilise.

Phone not powering on after the replacement cell sat in storage

Li-ion cells discharged below approximately 2.5V trip the BMS into a lockout state — the phone will not respond to the power button and may show no charge indicator at all. Connect the phone to a wall charger, not a USB port, and leave it for 20–30 minutes without attempting to power it on. The charge IC needs sustained input current to bring the cell voltage above the BMS recovery threshold before the phone's main board will initialise. Once the charging LED or screen indicator appears, the BMS has cleared the lockout and normal charging can continue.