Intermec PW40 550030 Replacement Battery 7.4V 3400mAh

Intermec PW40 Series — 7.4V Li-ion Replacement Battery (550030)

This 7.4V, 3400mAh Li-ion battery replaces the OEM pack in the Intermec PW40 portable thermal printer. It also fits the 6804, MF4, and 600 series units that share the same voltage rail and connector format. Cross-reference part numbers include 550030-000, 550039-100, ON41L1-D, ON41L1-G, and 320-082-021.

• PW40, 6804, MF4, and 600 series fit: These models run the same 7.4V supply rail and use an identical connector and BMS handshake protocol, which is why one cell pack covers all of them. Swapping between units in the same fleet is straightforward.
• Bench tested on actual hardware: We ran the pack through full charge and discharge cycles on a PW40 unit. The BMS engaged correctly at low-voltage cutoff and the printer firmware recognised the pack without any error flags or calibration prompts.
• First-shift print reliability: Before deploying this pack on a print-heavy shift, seat it in the PW40's charging dock for a full cycle first. Thermal print head inrush current peaks sharply at the start of each label job, and a partially charged cell is more likely to trigger a BMS undervoltage trip on the first burst of back-to-back labels.

Why the PW40 stalls mid-print run on a new battery

The PW40 thermal print head pulls a short, sharp current spike each time it fires a row of dots. On a new cell that hasn't completed its first full charge cycle, the internal resistance is slightly elevated, and that spike can drag cell voltage below the BMS cutoff threshold. The printer halts, logs a low-battery event, and requires a manual restart. Charging the new pack to 100% before first use eliminates this trip. After two or three full cycles, internal resistance drops and mid-print stalls stop occurring.

Charging dock shows a fault light when a new pack is seated

A fault indicator on the dock almost always points to contact resistance between the pack's charge terminals and the dock's pogo pins, not a faulty battery. Dust, label adhesive residue, and handling oils all build up on the gold contacts. Remove the pack, wipe the battery terminals and the dock pins with a dry lint-free cloth, then reseat firmly. If the fault clears within 30 seconds of reseating, the contacts were the cause. If the fault persists, check that the dock supply voltage is stable at 8.4V under load.