Brondi Amico Sprint Replacement Battery 3.7V 800mAh

Brondi Amico Sprint / Amico Del Cuore — 3.7V Li-ion Replacement Battery

This 3.7V 800mAh Li-ion cell replaces the original battery in the Brondi Amico Sprint and Amico Del Cuore mobile phones. Both models share the same battery bay dimensions (50 × 38 × 4.80mm) and voltage rail, making one cell compatible across both. Capacity is rated at 2.96Wh — identical to the factory spec.

• Amico Sprint and Amico Del Cuore compatibility: Both phones run the same 3.7V power rail with the same physical connector and bay geometry. The BMS handshake thresholds are matched, so the charge IC accepts this cell without triggering a fault flag on either model.
• Bench tested on actual hardware: We cycled this cell through charge and load on the bench. The BMS held cutoff at the correct low-voltage threshold and accepted a full charge without tripping an over-voltage fault at the top of the curve.
• Fuel gauge recalibration on first cycle: After fitting this cell, run one complete discharge down to auto-shutdown, then charge uninterrupted to 100% before resuming normal use. The phone's fuel gauge IC is calibrated to the old cell's discharge curve — one full cycle resets the coulomb counter reference and eliminates erratic percentage readings from the start.

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

A new Li-ion cell has a slightly different internal impedance profile than the aged cell the phone's power management IC was tracking. Under load — a call, a screen-on burst — the cell voltage can sag below the shutdown threshold even when the fuel gauge still reads 20–30%. This is a voltage-cliff issue, not a capacity defect. The fix is one full calibration cycle: discharge to auto-off, then charge to 100% without interruption. After that cycle, the fuel gauge IC maps the new cell's actual discharge curve and the premature shutdowns stop.

Phone won't power on after the replacement cell sat in storage

Li-ion cells self-discharge during storage. If the cell voltage drops below roughly 2.5V per cell, the BMS enters lockout mode to prevent damage and the phone will not respond to the power button. Connect the phone to a charger and leave it for 15–20 minutes without attempting to power it on — the charge IC trickle-charges the cell back above the BMS recovery threshold, typically around 2.9V. Once the charging indicator appears on screen, the BMS has exited lockout and normal charging resumes.