About this replacement
Pax A930 / A910 — 7.4V Li-Polymer Replacement Battery (JTH-J128)
This is a 7.4V, 2200mAh lithium-polymer replacement battery for the Pax A930 and A910 payment terminals. It fits the same slot and connector as the original JTH-J128 cell. Use it to restore full operation after the factory battery degrades or fails.
- A930 and A910 shared platform: Both terminals run the same 7.4V power rail, use the same physical housing dimensions, and share the BMS handshake protocol — so one cell covers both models without modification.
- Bench tested on actual hardware: We ran this cell through a full boot sequence on an A930 and monitored BMS communication. The charge IC accepted the cell within one complete power cycle, and the terminal reported state-of-charge without fault codes.
- First-transaction calibration: After fitting this battery, run one complete transaction from power-on through receipt print before placing the terminal in a live queue. The A930 maps battery capacity during normal operation — the charge indicator calibrates correctly only after at least one full power cycle under real load.
Terminal rebooting mid-transaction after a battery swap
The A930's receipt printer pulls a short, sharp current spike at the moment printing starts. On a freshly installed cell, the BMS has not yet learned the battery's internal resistance profile, so it can read that spike as an overcurrent event and trip protection. This causes an unexpected reboot — right at the point of sale. Running two or three test transactions before going live gives the BMS enough data to stop treating normal printer draw as a fault condition.
Terminal will not power on after sitting unused in a drawer
Li-polymer cells self-discharge at roughly 2–3% per month. A terminal stored for several months can drop below the BMS recovery threshold — typically around 2.5V per cell — and the device will not respond to the power button at all. Connect the terminal to the original charger and leave it undisturbed for 30–45 minutes before attempting to power on. If the charge LED does not light within five minutes of connecting, check the charger output voltage is at or above 8.4V before replacing the battery.