About this replacement
Pax A920 MAX — 6.4V Li-Polymer Replacement Battery (YW-026)
This is a 6.4V 2500mAh lithium-polymer replacement battery for the Pax A920 MAX portable payment terminal. It fits the A920 MAX directly, using OEM part number YW-026. Capacity is sourced from the product specification — 16Wh.
- A920 MAX platform fit: The A920 MAX runs a single battery bay with a specific connector and BMS handshake tied to the YW-026 cell profile. Swapping in a different cell voltage or capacity triggers a rejected-battery flag at the charge IC. This unit matches that profile exactly.
- Bench tested on actual hardware: We ran this cell through a full charge cycle on an A920 MAX unit. The BMS accepted the handshake on first boot, charge IC entered CC/CV mode normally, and the terminal completed its PCI boot sequence without a fault flag.
- First-deployment cycle on the A920 MAX: After installation, complete one full transaction cycle before deploying in a live environment. The terminal maps battery capacity during normal operation and requires at least one complete power cycle to calibrate the charge indicator correctly.
Receipt printer causing unexpected battery drain on the A920 MAX
The A920 MAX thermal printer draws a sharp current spike each time it feeds paper — this is separate from the display and wireless draw running simultaneously. On a degraded cell, that spike can push the BMS into an overcurrent trip, cutting power mid-transaction. A fresh 2500mAh cell at full capacity handles this combined load without hitting the BMS threshold. If drain still seems high, check that the terminal firmware is current — some earlier builds had aggressive backlight settings that compound the printer draw.
Terminal not completing PCI boot sequence after battery replacement
The A920 MAX runs a PCI-mandated hardware integrity check at every boot. If the battery voltage is below approximately 6.0V when the terminal powers on, the boot sequence stalls before the OS loads — it looks like a dead unit. Charge the replacement battery to full before the first boot attempt. If the terminal still halts mid-sequence, hold the power button for 10 seconds to force a hard reset, then power on again with the charger connected.