Dejavoo WHB02-2600 Q2 Payment Terminal Replacement Battery 7.4V

Dejavoo Q2 / QD2 / QD4 / WizarPOS Q2 — 7.4V Li-ion Replacement Battery (WHB02-2600)

This is a 7.4V, 2600mAh lithium-ion battery for the Dejavoo Q2, QD2, QD4, and WizarPOS Q2 portable payment terminals. It uses a 5-pin connector and matches the OEM part number WHB02-2600. Swap it in when your original battery no longer holds charge through a full shift of transactions.

• Q2 / QD2 / QD4 / WizarPOS Q2 compatibility: All four models share the same 7.4V battery architecture, 5-pin connector pinout, and BMS handshake protocol — one battery works across the entire range without any adapter or firmware difference.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Q2 terminal. The BMS accepted the handshake on first boot, charge IC reached full cutoff correctly, and the terminal reported battery status without error flags.
• Post-install calibration tip: 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.

Payment terminal rebooting mid-transaction after battery swap

The receipt printer motor draws a sharp current spike the moment it fires — on a Q2, that spike can reach 1.5–2A in under 50 milliseconds. If the BMS internal resistance threshold is set conservatively, it reads that spike as an overcurrent event and trips the protection circuit, cutting power mid-print. A new cell with a fully charged state reduces internal resistance and brings the transient well below the BMS trip point. If reboots continue after a full charge, check that the 5-pin connector is fully seated — any loose pin increases contact resistance and amplifies the voltage dip at the BMS sense line.

Terminal not completing PCI boot sequence after sitting unused in a drawer

Extended storage drains the cell below the PCI boot voltage floor — typically around 6.0V on a 7.4V Li-ion pack. When voltage drops that low, the BMS locks the output and the terminal cannot draw enough current to start the boot sequence at all. Connect the terminal to the OEM charger and leave it for 20–30 minutes before pressing the power button — the charger trickle-charges the cell back above the BMS recovery threshold first. Once the terminal boots and shows a charge screen, let it reach at least 7.2V before attempting a full restart.