About this replacement
Zebra QLN220 / QLN320 / ZQ510 / ZQ520 — 7.4V Li-ion Replacement Battery (P1031365-025)
This is a 7.4V, 4400mAh Li-ion battery for the Zebra QLN220, QLN320, ZQ510, and ZQ520 mobile thermal printers. It replaces OEM part numbers P1031365-025, P1023901, AT16004, P1051378, and several related variants. It fits directly into the original battery bay with no modification.
- QLN/ZQ platform compatibility: The QLN220, QLN320, ZQ510, and ZQ520 share the same 7.4V battery architecture, connector pinout, and BMS handshake protocol — which is why one cell fits across all four models. Voltage tolerance and charge termination logic are identical across this printer family.
- Bench tested on actual hardware: We ran this battery through full charge and discharge cycles on a QLN320. The BMS responded correctly to charge termination at 8.4V, and the thermal head and paper feed motor drew stable current throughout the cycle without triggering overcurrent cutoff.
- First-deploy print sequence: After fitting a new battery, charge it fully and print five test labels before putting the unit into production. The paper feed motor pulls a short current spike on each print cycle, and running these calibration prints confirms the BMS current profile is correctly matched to the new cells.
Why the QLN220 disconnects from Bluetooth mid-job
The QLN220 runs its Bluetooth radio from the same battery rail as the thermal head and paper feed motor. When the battery voltage sags under combined load — particularly during a print cycle — the radio doesn't get enough power to maintain its link budget and drops the connection. This happens most often when the battery is partially discharged, because internal resistance rises and voltage sag under load becomes more pronounced. Keeping the battery above 50% charge during heavy print runs prevents the radio from competing with the thermal head for voltage headroom.
Print output fading or going uneven after battery swap
The thermal print head in the QLN220 and ZQ510 is temperature-sensitive — it needs a stable voltage supply to maintain consistent dot energy across each print line. If a new battery hasn't completed a full charge cycle before deployment, its output voltage under load can fluctuate enough to cause uneven head temperature, which shows up as faded stripes or patchy barcodes. This is not a head fault. Charge the battery fully to 8.4V before the first use, then run the five-label test sequence to let the BMS settle into the correct current profile for the new cells.