Amazing A3 Replacement Battery 3.7V 1200mAh Li-ion

Amazing A3 / A3s — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1200mAh Li-ion replacement battery for the Amazing A3 and A3s smartphones. It fits directly where the original cell sits and restores power to the device for calls, messaging, and app use. Swap it when the original cell no longer holds a usable charge through a normal day.

• A3 and A3s compatibility: Both models share the same battery bay dimensions and 3.7V nominal voltage rail. The connector pinout and BMS handshake are identical across the two variants, so one cell covers both.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the A3 platform. The BMS accepted the charge IC handshake without fault codes, and protection cutoffs triggered correctly at both the low-voltage floor and the full-charge ceiling.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-to-charge cycle at standard rate. This lets the fuel gauge IC build an accurate discharge curve against the new cell before high-current charging pushes into an uncalibrated state.

Sudden shutdown at 20–30% on the Amazing A3 after a cell swap

The A3's fuel gauge IC stores a learned discharge curve from the original cell. A new cell with a different internal resistance profile will hit the voltage cutoff threshold sooner than the gauge predicts under modem or screen load. The phone reads 25% remaining, but the actual cell voltage drops below the BMS floor under load and the device shuts off. One full discharge-charge cycle at standard rate lets the coulomb counter recalibrate — after that, the reported percentage and real cell state align.

Phone shows incorrect or jumping battery percentage after replacement

The fuel gauge IC on the A3 is calibrated to the impedance curve of the original cell. A fresh cell has lower internal resistance, which shifts the voltage-to-capacity mapping the IC uses. This makes the percentage reading jump or land consistently high or low. Run the phone from 100% down to automatic shutdown without charging in between, then charge fully to 100% uninterrupted — the IC rewrites its reference curve after that cycle and the display stabilises.