About this replacement
Sunmi V2 Pro — 7.6V Li-Polymer Replacement Battery (ZQP1659)
This 7.6V, 2100mAh Li-Polymer battery replaces the ZQP1659 cell in the Sunmi V2 Pro portable payment terminal. It fits the compact handheld POS device used by merchants in retail and hospitality settings. Capacity is 2100mAh (15.96Wh), matching the original specification.
- V2 Pro platform fit: The V2 Pro uses a specific connector pinout and BMS handshake tied to the ZQP1659 cell profile. This replacement carries the correct cell geometry (68.60 × 56.50 × 7.40mm) and communicates with the terminal's charge IC without triggering a rejection error.
- Bench tested on actual hardware: We cycled this cell through the V2 Pro's charge IC and confirmed the BMS accepts the handshake, reaches full charge without fault codes, and holds voltage under combined display, wireless, and printer draw.
- First transaction cycle after installation: After fitting this battery, complete one full transaction — tap to receipt print — before deploying in a live environment. The V2 Pro maps capacity during normal operation and needs at least one complete power cycle to calibrate the charge indicator accurately.
Payment terminal rebooting mid-transaction after battery swap
The V2 Pro's receipt printer motor pulls a short current spike at the moment it feeds paper. On a new cell that hasn't completed its first full charge cycle, the BMS can interpret that spike as an overcurrent event and cut output to protect the cell. This trips the terminal mid-sale — usually right after card approval when the printer fires. Let the battery reach a full charge before the first live transaction, and the BMS will have calibrated its overcurrent threshold against actual load data rather than factory defaults.
Terminal not powering on after sitting unused in a drawer
Li-Polymer cells self-discharge over time. If the V2 Pro sat unused for several weeks, the cell voltage may have dropped below the BMS recovery threshold — typically around 2.5V per cell — and the terminal will show nothing when you press power. Connect the charger and leave it for 20–30 minutes without pressing anything. The charge IC needs to trickle-charge the cell back above the recovery floor before normal charging begins. If the charging indicator appears within that window, the cell is recovering; if nothing shows after 45 minutes on charge, the original cell has likely failed below recoverable voltage and replacement is the correct next step.