About this replacement
Pax A920 Pro — 3.7V Li-Polymer Replacement Battery (YW-008)
This 3.7V, 5150mAh Li-Polymer battery is a direct replacement for the Pax A920 Pro mobile payment terminal. It fits the A920 Pro and restores power capacity to this merchant-facing POS device. Part number YW-008 matches the original cell format at 70 x 60 x 10mm.
- A920 Pro platform fit: The A920 Pro uses a single Li-Polymer cell with a specific connector and BMS handshake. This cell matches that voltage rail and connector layout so the terminal's charge controller recognises it without throwing a battery fault code.
- Bench tested on actual hardware: We cycled this cell through the A920 Pro's charge IC and confirmed the BMS accepted the handshake on first boot. The charge controller entered normal CC/CV charging without tripping a protection flag.
- First deployment tip for POS terminals: After installation, complete one full transaction cycle before deploying in a live environment. The A920 Pro maps battery capacity during normal operation and requires at least one complete power cycle to calibrate the charge indicator correctly.
Payment terminal rebooting mid-transaction after battery swap
The A920 Pro's receipt printer and wireless radio draw current simultaneously during a transaction. On a new cell, the BMS protection threshold can trip during this combined load spike before the cell has completed its first full charge cycle. The BMS reads the surge as an overcurrent event and cuts output to protect the cell. Run the terminal through one complete charge before putting it into a live transaction environment — that cycle allows the BMS to set its overcurrent baseline against the actual cell capacity.
Terminal not completing PCI boot sequence after sitting unused
If an A920 Pro sits unused for an extended period, the cell can self-discharge below the BMS recovery threshold — typically under 2.5V per cell. At that voltage, the BMS locks out discharge and the terminal won't complete its PCI boot sequence or show any sign of life. Connect the terminal to its original charger and leave it undisturbed for at least 30 minutes to allow the charge IC to trickle-charge the cell back above the recovery threshold. Once the cell reaches approximately 3.0V, the BMS unlocks and normal charging resumes.