Pax S920 Payment Terminal Compatible Battery 3.7V 3350mAh

Pax S920 — 3.7V Li-ion Replacement Battery (IS1112)

This 3.7V 3350mAh Li-ion battery replaces the original cell in the Pax S920 portable payment terminal. It fits the S920 directly, using OEM part numbers IS1112 and IS486. Voltage and capacity match factory spec — 3.7V, 3350mAh (12.4Wh).

• S920 platform fit: The S920 uses a single-cell Li-ion pack with a multi-pin connector that carries both power and BMS communication lines. The terminal's charge IC negotiates cell state with the pack on every boot — voltage, chemistry, and connector pinout must match exactly or the terminal rejects the battery.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the S920 platform. The BMS handshake completed on first boot, the charge IC entered CC/CV mode without fault codes, and the cell held voltage within expected tolerance across multiple transaction loads including simultaneous printer and wireless draw.
• First-deployment cycle: After installation, complete one full transaction cycle before putting the terminal into live service. The S920 maps battery capacity during normal operation and needs at least one complete power cycle to calibrate the charge indicator correctly — skipping this leaves the gauge reading inaccurate from the start.

Receipt printer current spike triggering mid-transaction reboots

The S920's thermal receipt printer pulls a sharp current spike the moment it starts printing — this happens at the end of every approved transaction. A degraded or deeply discharged cell can't sustain the combined load of the wireless radio, display, and printer motor simultaneously. The BMS reads this as an overcurrent event and trips, cutting power to the terminal mid-sale. A fresh cell at full charge handles the spike without the BMS intervening — the cell voltage should not sag below 3.4V under this combined load.

Terminal not powering on after sitting unused in a drawer

Li-ion cells self-discharge over time, and the S920's standby draw accelerates this if the terminal was left partially charged. Once cell voltage drops below approximately 2.5V, the BMS enters a locked low-voltage state and blocks normal charging to protect the cell. The terminal shows nothing — no boot screen, no charge indicator — and appears completely dead. Connect to the OEM charger and leave it undisturbed for 30–60 minutes; the charge IC will attempt a low-current recovery pulse to bring the cell back above the 2.8V threshold before switching to normal charge mode.