Honeywell Intermec PB20A Microflash 4i Replacement Battery 7.4V

ONeil Microflash 4i / 4T Series — 7.4V Li-ion Replacement Battery (PB20A)

This 7.4V, 2400mAh Li-ion battery replaces the OEM pack in ONeil Microflash 4i, 4tCR, and 4T mobile printers. It also cross-references part numbers PB40, PB41, PW40, and 550034-000, covering the broader Microflash 4T family. Capacity is 17.76Wh, matching the original draw profile of the print head and wireless radio combined.

• Microflash 4i / 4T platform fit: These models share the same 7.4V battery bay, connector pinout, and BMS communication protocol — one pack covers the full series. The print head, wireless module, and label feed motor all run off the same cell group, so voltage tolerance and BMS trip thresholds are identical across variants.
• Bench tested on actual hardware: We cycled this pack through repeated print-and-feed sequences on the Microflash platform, monitoring BMS response during print head inrush and wireless polling intervals. The BMS held stable across the full discharge curve without nuisance tripping at either end.
• First-shift prep for the Microflash 4T: Before using on a pick-and-pack shift, seat the pack in the cradle and let it complete a full charge cycle. Print head inrush at the start of a label burst is highest when the cell is near minimum — a fully charged pack prevents a false BMS cutoff during the first print job of the shift.

Why the Microflash 4T drops wireless mid-print run

The Microflash 4T draws from the battery simultaneously during label feed, print head firing, and wireless acknowledgment packets. When the cell voltage sags under that combined load — especially late in a shift — the radio subsystem is first to drop because the BMS prioritises the print head rail. The result looks like a wireless dropout but the root cause is voltage sag, not signal loss. A fresh pack at full charge keeps the voltage above the radio's minimum operating threshold through the entire burst sequence.

Cradle showing a charging error after fitting a new pack

A charging error on a new pack almost always comes from contact resistance at the dock, not a faulty battery. Dust, label adhesive residue, and oxidation on the gold contact pads block the handshake signal between the pack and the cradle's charge controller. Wipe the three contacts on the battery and the corresponding dock pins with a dry lint-free cloth, then reseat the pack firmly until it clicks. If the error clears within 30 seconds of reseating, the contacts were the cause — no further action needed.