M3 Mobile UL20F Replacement Battery 3.7V 5200mAh Li-ion

M3 Mobile UL20F / UL20 — 3.7V Li-ion Replacement Battery (UL20-BATT-F67)

This is a 3.7V, 5200mAh Li-ion replacement battery for the M3 Mobile UL20F and UL20 rugged handheld barcode scanners. It matches the OEM part number UL20-BATT-F67 and fits the same battery bay without modification. Both voltage and capacity figures match the original pack specification.

• UL20F and UL20 platform fit: Both models share the same 3.7V power rail, battery bay dimensions, and BMS handshake protocol — one pack covers either unit. The connector pinout and communication lines are identical across the range.
• Bench tested on actual hardware: We ran this pack through charge and discharge cycles on the UL20 platform. The BMS responded correctly to charge termination and low-voltage cutoff. No false trips or charge refusal occurred during testing.
• First-shift preparation on cradle-charged devices: After installing this pack, seat the scanner in its cradle and let it complete a full charge cycle before the first pick-and-pack shift. Scan trigger inrush current is highest when the cell is near minimum charge — starting fully charged prevents the BMS from tripping on that first burst of rapid scans.

Cradle showing a charging error on a new pack

A charging dock error on a freshly installed pack is almost always a contact resistance issue, not a fault with the cell itself. Dock contacts and battery terminals accumulate oxide and debris in warehouse environments, and even a small resistance increase can push the voltage drop outside the charger's acceptance window. Wipe the gold contacts on the battery and the dock pins with a dry lint-free cloth, then reseat the pack firmly. If the error clears, the cell charges normally — the dock was reading the contact drop as a pack fault.

Scanner losing wireless connection during rapid scan bursts

During a rapid scan sequence, the imager trigger current and the wireless radio transmit pulse hit the battery at the same time. If the pack voltage sags below the radio module's minimum operating threshold in that window, the wireless stack drops and the scanner appears to freeze or disconnect. This is more pronounced with a degraded original pack but can also occur if a new replacement pack is installed below 30% charge. Charge the new pack fully in the cradle before field use — a full cell absorbs the combined inrush without the voltage sag that trips the radio.