Aligator A290 Replacement Battery 3.7V 1200mAh Li-ion

Aligator A290 / A330 / A350 / A400 Series — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1200mAh Li-ion battery for the Aligator A290, A330, A350, A400, and compatible models in the same series. It replaces the original cell when the phone no longer holds a useful charge between sessions. Dimensions are 53.00 × 34.00 × 5.70mm — verify against your existing battery before fitting.

• Multi-model fit across the Aligator budget series: The A290, A330, A350, and A400 share the same battery bay dimensions and 3.7V single-cell architecture. The connector pinout and BMS handshake protocol are consistent across these models, which is why one cell covers the group.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge passes on a compatible handset. The BMS held protection thresholds correctly and the charge IC accepted current without triggering cutoff prematurely.
• Fuel gauge recalibration on first use: After fitting this battery, run one complete discharge down to auto-shutoff, then charge to 100% uninterrupted. This gives the phone's fuel gauge IC a full reference curve to map the new cell — skipping this step causes erratic percentage readings in the first few days of use.

Sudden shutdown at 20–30% on the Aligator A290 after a cell swap

This is a voltage cliff problem, not a capacity problem. The Aligator A290's modem and display draw a combined load spike that a freshly installed, uncalibrated cell cannot sustain at lower state-of-charge. The cell voltage drops momentarily below the BMS cutoff threshold — around 3.0V under load — and the phone shuts off even though the fuel gauge still shows charge remaining. One full reference cycle resolves this in most cases: discharge to auto-shutoff, charge to 100%, then repeat once more if the shutdowns persist.

Phone not powering on after the replacement battery sat in storage

Li-ion cells self-discharge during storage. If this battery has been stored a long time before installation, the cell voltage may have dropped below 2.5V — the threshold at which the BMS enters lockout mode to prevent damage. The phone will show nothing when you press the power button. Connect the phone to a charger and leave it for 15–20 minutes without attempting to power on; the charge IC will trickle current into the cell to bring it above the BMS recovery threshold, typically around 2.9V, before normal charging resumes.