Aligator V500 Replacement Battery 3.7V 900mAh Li-ion

Aligator V500 / V550 / A420 — 3.7V Li-ion Replacement Battery

This is a 3.7V, 900mAh Li-ion cell for the Aligator V500, V550, and A420 smartphones. It replaces the original factory cell when capacity has faded to the point where the phone no longer holds charge through a normal day. Physical dimensions are 46.47 × 39.79 × 5.33mm — confirm these against your existing cell before fitting.

• V500, V550, and A420 cell compatibility: These three models share the same battery bay geometry and 3.7V single-cell architecture. The connector pinout and cell footprint are identical across the group, so one replacement cell covers all three.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench and monitored BMS cutoff behaviour. The protection circuit held the low-voltage cutoff correctly and did not trigger premature shutoff under steady load.
• Fuel gauge recalibration after fitting: On first use after installation, run one complete discharge down to automatic shutoff before recharging to 100%. This gives the fuel gauge IC one full reference cycle against the new cell's actual discharge curve before the OS starts reporting percentage to the screen.

Sudden shutdown at 20–30% on the V500 after a cell swap

The V500's fuel gauge IC stores a discharge curve calibrated to the original cell. A new cell with a different internal impedance profile hits a voltage cliff at a different state of charge than the IC expects. When the modem or screen pulls a short high-current burst, the cell voltage drops below the BMS cutoff threshold even though the reported percentage reads 25–30%. The fix is one full discharge-to-shutoff cycle followed by a full charge — this lets the coulomb counter reset its endpoints against the real cell. After that cycle, the reported percentage and actual cutoff voltage align correctly.

Phone not powering on after the replacement cell sat in storage

Li-ion cells self-discharge in storage, and if the voltage drops below approximately 2.5V per cell, the BMS latches into lockout mode to prevent damage. The phone will show no response at all — no boot logo, no charge indicator. Connect the phone to a wall charger rather than a PC USB port, which supplies lower current. Leave it connected for 15–20 minutes before attempting to power on; the charger IC needs enough headroom above the lockout threshold to wake the BMS and begin a trickle pre-charge back to 3.0V.