About this replacement
Intermec PB21 / PB22 / PB31 / PB32 — 7.4V Li-ion Replacement Battery (318-030-001)
This is a 7.4V 2600mAh Li-ion battery for the Intermec PB21, PB22, PB31, and PB32 mobile thermal printers. These printers are used in retail, logistics, and field service for on-the-spot receipt and label printing away from fixed power. It replaces OEM part numbers 318-030-001, 318-030-003, and AB27.
- PB21 / PB22 / PB31 / PB32 compatibility: All four models share the same 7.4V battery platform, connector pinout, and BMS handshake protocol. One cell fits all four without modification.
- Bench tested on actual hardware: We ran this battery through a full charge-discharge cycle on the PB21. The BMS negotiated cleanly, the thermal head reached operating temperature without voltage sag, and the paper feed motor drew current within expected range under continuous print load.
- First-use print sequence: After installing, charge the battery fully, then print five test labels or receipts before deploying. The paper feed motor and thermal head together draw a combined current spike on first use — running this sequence confirms the BMS current profile is correctly set for the new cell.
Why the PB21 stops printing after sitting unused for weeks
Li-ion cells self-discharge during storage. The PB21's BMS has a low-voltage lockout that engages when the cell drops below roughly 6.0V — the printer powers on but refuses to drive the thermal head or feed motor. Placing the printer on charge for 30–60 minutes before use is enough to push the cell above the BMS re-enable threshold. If the printer still won't print after charging, hold the power button for 10 seconds to force a BMS re-initialisation cycle.
Faded or uneven print on a battery that shows charge
The PB21 thermal head needs a stable voltage to maintain consistent head temperature across the full print width. When a degraded cell sags under thermal head current draw, head temperature drops mid-line, producing faded or patchy output. The battery gauge can show 50% or more while this is happening because gauge accuracy degrades with cell age. If print quality improves significantly when the printer is on mains power, the cell has lost capacity and needs replacement — not a print density setting adjustment.