Amazing A1 Smartphone Replacement Battery 3.7V 1500mAh

Amazing A1 — 3.7V Li-ion Replacement Battery

This is a 3.7V 1500mAh Li-ion replacement battery for the Amazing A1 smartphone. It fits the A1's battery bay and connects via the original flex connector. Capacity matches the factory specification at 5.55Wh.

• Amazing A1 fit: The A1 uses a single-cell 3.7V nominal Li-ion pack. This cell matches that voltage rail, physical dimensions (49.00 × 47.80 × 5.50mm), and connector orientation — so the BMS on the motherboard receives the handshake it expects at power-on.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the A1 platform. The BMS accepted the cell without error flags, charge termination triggered correctly at 4.2V, and the protection circuit tripped as expected at the low-voltage cutoff threshold.
• Fuel gauge recalibration after swap: On first use after installing this cell, disable fast charging and run one full discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging begins on an uncalibrated reference.

Sudden shutdown at 20–30% on the Amazing A1 after a cell swap

The A1's fuel gauge IC was calibrated to the discharge curve of the original cell. A new cell has a slightly different internal resistance profile, so the voltage sag under modem and screen load hits the low-voltage cutoff before the reported percentage reaches zero. The phone cuts power abruptly at what the gauge still reads as 20–30%. One full discharge cycle — letting the phone run down to automatic shutdown, then charging uninterrupted to 100% — resets the coulomb counter reference and tightens the percentage-to-voltage mapping. After that cycle, shutdowns should align with single-digit percentages.

USB fast charge not activating on the first cycle after replacement

When a new cell is installed, the charge IC on the A1 motherboard reads elevated internal impedance on the fresh cell and may restrict current delivery, keeping the connection in standard 5V charging rather than negotiating the fast-charge protocol. This is a protective behaviour — the IC is limiting inrush until it has completed one charge profile on the new cell. Plug into a standard 5V charger (not a fast-charge adapter) for the first complete charge cycle. After that cycle, reconnect the fast charger — the IC will renegotiate the protocol and fast charging should resume normally.