About this replacement
Casio IT-G400 — 3.85V Li-ion Replacement Battery (HA-R21LBAT)
This is a 3.85V 5800mAh Li-ion battery for the Casio IT-G400 handheld barcode scanner. It matches OEM part number HA-R21LBAT and fits directly into the IT-G400's battery bay. The IT-G400 is used across retail and warehouse environments for continuous scanning and inventory work.
- IT-G400 platform fit: The IT-G400 runs a 3.85V power rail and uses a BMS handshake that expects a specific charge profile. This pack matches that voltage and communicates correctly with the onboard battery management circuit — no false low-battery alerts or charge rejection at the dock.
- Bench tested on actual hardware: We cycled this pack through repeated scan-trigger and wireless radio loads — the two highest simultaneous draws the IT-G400 produces. The BMS held stable through each burst without tripping into protective cutoff.
- First-shift preparation: After installing, seat the scanner in its cradle and run a full charge before the first pick-and-pack shift. Scan trigger inrush is highest when the cell sits near minimum charge — a fully charged pack prevents the BMS from tripping on the very first trigger pull of the day.
Cradle showing a charging error on a new pack
A charging error on a fresh pack is almost always a contact issue, not a battery fault. The IT-G400 cradle reads pack state through gold pogo pins — any oxidation or debris on the pack's contact pads raises resistance enough to trigger an error flag. Remove the pack, wipe the contacts on both the battery and the cradle with a dry cloth, then reseat firmly. If the error clears within 30 seconds, contact resistance was the cause.
Scanner losing wireless connection during rapid scan bursts
During a fast scan sequence, the IT-G400 fires the imager and transmits data over Wi-Fi or Bluetooth simultaneously. That combined inrush can pull the pack voltage down sharply if the cell is partially discharged. The radio stack drops connection first — it has a lower minimum voltage threshold than the scanner's CPU. Start shifts with a fully charged pack and check that the battery indicator reads above 40% before any high-frequency scan run.