About this replacement
HPRT A300 / A318 / A330 / Z3 Series — 7.4V Li-ion Replacement Battery (KM300BU)
This is a 7.4V 1600mAh Li-ion battery replacing OEM part KM300BU in HPRT portable thermal receipt printers. It fits the A300, Z3, A318, and A330 models used in mobile point-of-sale, restaurant, and logistics environments. Voltage and cell chemistry match the original specification exactly.
- A300 / A318 / A330 / Z3 platform compatibility: These models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The KM300BU form factor — 79.85 × 40.34 × 21.42mm — is consistent across the series, so one battery fits all four variants without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on an A300 unit. The BMS accepted the new cell without fault codes, thermal head voltage held steady across multiple print jobs, and the paper feed motor drew current within normal limits throughout testing.
- First-use print sequence: After installing and fully charging, print five test receipts before deploying in a live environment. The paper feed motor draws a calibration-level current burst on each feed cycle — running this sequence confirms the BMS has correctly profiled the new cell under real motor load conditions.
Bluetooth dropping mid-print job on the A300
The A300's Bluetooth radio and thermal head fire simultaneously during a print job. At low battery, the combined current draw causes a voltage sag that pulls the supply rail below the radio's minimum operating threshold. The Bluetooth stack drops the connection before the print job completes — the device appears functional but stops mid-receipt. Charge the battery to full and confirm resting voltage reads at least 8.0V before returning the unit to service.
Faded or uneven print on a freshly installed battery
The thermal print head requires a stable, consistent voltage to maintain the correct element temperature across the full print width. If the replacement cell's BMS hasn't yet profiled the load, it can throttle output on the first few cycles, causing the head to run cooler than spec and produce faint or patchy text. This is not a head fault. Run the five-receipt calibration sequence described above — output typically normalises by the third receipt as the BMS locks onto the correct current delivery curve.