Bea-fon SL560 Replacement Battery 3.7V 650mAh Li-ion

Bea-fon SL560 / SL450 — 3.7V Li-ion Replacement Battery (SL560/SL450)

This 3.7V 650mAh Li-ion cell replaces the original battery in the Bea-fon SL560 and SL450 mobile phones. Both handsets share the same battery bay geometry and connector, making a single cell compatible across both models. Capacity is 650mAh (2.41Wh), matching OEM specification.

• SL560 and SL450 shared platform: Bea-fon built the SL560 and SL450 on a common hardware platform — same voltage rail at 3.7V, same physical connector orientation, and the same BMS handshake protocol. One cell covers both.
• Bench tested on actual hardware: We cycled this cell on the SL560 through charge and discharge under screen-on and call-active loads. The BMS held cutoff correctly at both ends of the charge window with no false low-battery trips.
• Fuel gauge recalibration after installation: On first use after fitting this cell, disable any fast-charge mode and run one full discharge-charge cycle before normal use. This lets the fuel gauge IC map the new cell's actual discharge curve before high-current charging pushes current into an uncalibrated state.

Sudden shutdown at 20–30% on the SL560 after a cell swap

The SL560 uses a coulomb-counter fuel gauge that was calibrated against the original cell's internal resistance and discharge curve. A new cell has lower impedance, so the gauge underestimates remaining capacity and triggers a low-voltage cutoff too early — usually at the 20–30% mark. The phone isn't actually out of charge; the gauge is reading the wrong voltage cliff. One full discharge down to auto-off, followed by an uninterrupted charge to 100%, resets the counter and brings percentage reporting back into line.

Phone won't power on after sitting in storage with a flat battery

If the SL560 or SL450 has been stored discharged for weeks, the cell can drop below 2.5V — the threshold where the BMS locks out to prevent damage. The phone will show nothing when you press the power button, and may not respond to a charger on the first attempt. Plug in a charger and leave it connected for 20–30 minutes without attempting to power on; most BMS circuits on these cells will accept a trickle recovery current and release the lockout once the cell climbs back above 2.9V. If the phone then shows a charge indicator, let it reach full charge before powering on.