ONeil RP4 Receipt Printer Replacement Battery 7.4V 6800mAh

ONeil RP4 — 7.4V Li-ion Replacement Battery (550053-000)

This is a 7.4V Li-ion battery rated at 6800mAh (50.32Wh), built to replace part number 550053-000 in the Honeywell ONeil RP4 mobile receipt printer. The RP4 is a portable thermal printer used in retail, logistics, and hospitality for on-the-go receipt and label printing. When original cells degrade, this pack restores full operating voltage to the print head, paper feed motor, and wireless radio.

• RP4 platform fit: The RP4 uses a 7.4V nominal rail to drive the thermal print head, paper feed motor, and Bluetooth radio from a single cell pack. All three subsystems share this voltage bus, so a weak cell affects print quality, paper feed torque, and wireless stability at the same time.
• Bench tested on actual hardware: We ran this pack through charge and discharge cycles on the RP4 and confirmed the BMS handshake completed without fault flags. The protection circuit responded correctly to motor-start current draw from the paper feed mechanism and held voltage within the thermal head's operating range.
• First-use print sequence: After installing and fully charging, print five test receipts before deploying in the field. The paper feed motor draws a calibration-level current pulse on each cycle, and running this sequence confirms the BMS has correctly profiled the load signature of the new cells.

Why the RP4 refuses to print after sitting unused for weeks

Li-ion cells self-discharge during storage. If the RP4 sits unused long enough, the pack voltage drops below the printer's minimum motor drive threshold — typically around 6.8V for the RP4's feed mechanism. At that point, the firmware blocks printing to protect the thermal head from under-voltage operation. Connecting to charge and waiting for the pack to recover past that threshold is the fix. Do not attempt to print during the recovery charge — let it reach at least 7.0V first.

Faded or uneven print output on a freshly installed battery

The thermal print head on the RP4 requires a stable voltage to heat elements evenly across the print line. If voltage sags mid-print — common when a new pack hasn't completed its first full charge — some elements don't reach target temperature and leave faint or missing lines on the receipt. This is not a head fault. Charge the pack fully (to 8.4V), then run the five-receipt test sequence. Print quality normalises once the BMS has established the correct current profile for the load.