Symbol WT4000 Barcode Scanner Replacement Battery 3.7V 3400mAh

Symbol WT4000 / WT41N0 Series — 3.7V Li-ion Replacement Battery (BTRY-WT40IAB0E)

This 3.7V, 3400mAh Li-ion battery replaces the original pack in the Symbol WT4000, WT4090, WT4090i, and WT41N0 wrist-mount mobile computers. These devices run barcode scanning and wireless data collection in warehouse, retail, and logistics environments. OEM part numbers covered include 55-000166-01, BTRY-WT40IAB0E, BTRY-WT40IAB0H, 82-90005-05, and 82-90005-03.

• WT4000 / WT41N0 platform fit: These models share a common 3.7V cell format, identical connector pinout, and the same BMS handshake protocol — the dock, charge cradle, and device firmware all read the same pack identification registers across this series.
• Bench tested on actual hardware: We cycled this pack through full charge and discharge on a WT41N0 unit. The BMS flagged charge acceptance correctly, terminated at 4.2V, and held low-voltage cutoff at 3.0V without triggering a false over-current fault during scan-trigger inrush.
• First-shift preparation for wrist scanners: After installing, seat the scanner in its cradle for a full charge cycle before starting pick-and-pack work. Scan trigger inrush current peaks when the cell is near minimum — a fully charged pack prevents a false BMS trip on the opening scans of the first shift.

Cradle showing a charging error on a new pack

WT4000-series cradles authenticate the battery over the charge contacts before allowing current flow. If those contacts carry oxidation or debris from a worn original pack, the new cell gets a high-resistance handshake and the dock flags a charge fault — not a battery fault. Clean the gold contacts on both the pack and the cradle with a dry lint-free cloth, reseat firmly, and check that the charge LED moves to solid amber within 30 seconds. If the error clears, the cell was fine all along.

Scanner losing wireless connection during rapid scan bursts

During a fast scan sequence, the WT4000 draws current simultaneously from the imager and the 802.11 radio — both spike at the same moment. If the cell voltage sags below roughly 3.4V under that combined load, the radio drops its association before the scan engine fails, so the user sees a connection drop rather than a scanning error. This is a cell-condition issue, not a radio issue. A pack at full charge handles the combined inrush without a sag event; a partially depleted or aged cell cannot. Charge the pack to 4.2V before a high-throughput shift.