About this replacement
Zebra MC33 Series — 3.7V Li-ion Replacement Battery (BT-000337)
This 3.7V, 6800mAh (25.16Wh) battery replaces the original pack in the Zebra MC33, MC330, MC330K, and MC330M mobile computers. These are rugged handheld scanners used in warehouse, retail, and field service operations. The battery slots into the same bay as OEM parts BT-000337, BT-000338, and BTRY-MC33-27MA-01.
- MC33 family fit: The MC33, MC330, MC330K, and MC330M all share the same battery bay geometry, connector pinout, and BMS communication protocol — one pack covers all four variants without modification.
- Bench tested on actual hardware: We ran this pack through the MC33 charging cradle and confirmed the BMS handshake completes correctly, the device exits charge mode at full cell voltage, and the scan trigger fires without fault codes on a fresh install.
- First-shift cradle protocol: After installing, seat the scanner in its charging cradle for a full charge cycle before putting it on a pick-and-pack shift. Scan trigger inrush current peaks when the cell is near minimum, and a fully charged pack prevents false BMS trips during the first burst of rapid scanning.
Why the MC33 drops its wireless connection during rapid scan bursts
The MC33 draws current from two sources simultaneously during a rapid scan sequence — the imager or laser, and the 802.11 radio keeping the session alive with the access point. When the cell voltage sags under that combined load, the radio is the first subsystem to lose stable power. The BMS interprets the voltage dip as a protection threshold event and briefly throttles output. The fix is ensuring the cell starts a heavy scanning shift at or above 3.9V — below that, combined inrush from radio plus imager is enough to trigger the sag.
Charging cradle showing an error light on a new pack
A new pack placed in the cradle sometimes returns a fault LED rather than a charge indicator. The most common cause is contact resistance at the battery terminals — either residue from packaging or a misaligned seating in the dock. Remove the pack, wipe the gold contacts on both the battery and cradle with a dry cloth, then reseat firmly until you hear the latch click. If the error clears and charging begins, the contacts were the issue; if the fault persists, check that cradle firmware supports the BT-000337 cell capacity by confirming the cradle model against Zebra's compatibility matrix.