Symbol ES400 Barcode Scanner Battery BTRY-ES40EAB00 3.7V

Symbol ES400 / ES405 — 3.7V Li-ion Replacement Battery (BTRY-ES40EAB00)

This is a 3.7V, 1500mAh Li-ion cell that replaces the original battery in the Symbol ES400 and ES405 handheld barcode scanners. Both models run the same voltage rail and use the same OEM part number, so one replacement covers either unit. Capacity matches the product spec at 5.55Wh.

• ES400 and ES405 compatibility: Both scanners share the same battery bay dimensions, connector pin-out, and BMS handshake protocol. A single cell services either unit without modification or adapter.
• Bench tested on actual hardware: We cycled this pack through the ES400's charge management circuit and confirmed the BMS initialised correctly, reported accurate state-of-charge to the device OS, and held the full 1500mAh within tolerance across discharge cycles.
• First-shift preparation: After installing, seat the scanner in its cradle and run a full charge cycle before the first pick-and-pack shift. The scan trigger inrush current peaks when the cell is near minimum voltage — a fully charged pack on day one prevents false BMS trips that can misread as hardware faults.

Cradle showing a charging error on a new pack

The ES400 cradle uses spring contacts to communicate charge state between the dock and the battery. Oxidation or debris on those contacts raises resistance enough to trigger a charging fault even when the pack is good. Wipe the gold contacts on both the battery and the cradle with a dry cloth, then reseat the scanner firmly. If the error clears within 30 seconds of reseating, the contacts were the cause — not the cell or the dock electronics.

Scanner losing wireless connection during rapid scan bursts

The ES400 draws simultaneously from the wireless radio and the scan engine during high-frequency scanning. If the battery cell resistance is elevated — common in aged packs — voltage sags briefly under that combined load, and the wireless module drops its connection before the scan engine does. A fresh cell with lower internal resistance handles the combined inrush without the sag. After swapping the battery, confirm the device reconnects to your network and holds the link through at least 20 consecutive rapid scans before returning it to the floor.