Vertex Standard VX-D281 Replacement Battery 7.4V 1800mAh

Vertex Standard VX-D281 Series — 7.4V Li-ion Replacement Battery

This 7.4V 1800mAh Li-ion battery replaces the OEM pack on the Vertex Standard VX-D281, VX-D28I, and VX-D288 portable two-way radios. These are handheld digital radios used in public safety, security, and commercial land mobile radio operations. The physical dimensions are 96.05 × 53.30 × 32.82mm, matching the original battery bay on all three variants.

• VX-D281, VX-D28I, and VX-D288 compatibility: All three models share the same battery bay geometry, contact layout, and BMS handshake protocol. One replacement pack covers the full variant range without modification.
• Bench tested on actual hardware: We cycled this pack through full charge and transmit-load discharge on the VX-D281 platform. The BMS held cutoff correctly at the low-voltage threshold and accepted a full recharge cycle without fault.
• First insertion contact check: If the charger dock shows a fault LED on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The Vertex Standard platform requires a clean contact cycle to complete the BMS handshake before charging begins.

Why the VX-D281 cuts out mid-transmission on a freshly inserted battery

When a new Li-ion pack ships at storage voltage — typically around 3.7V per cell, or roughly 7.4V total — the BMS may interpret the transmit current spike as an overcurrent event and trip the protection circuit before the radio completes a transmission. This is not a faulty battery. The VX-D281's PTT draw can exceed 1.5A instantaneously, and a cold BMS on a pack that hasn't completed a conditioning charge is more likely to trip at that threshold. Charge the pack fully to 8.4V before the first operational use. After one complete charge cycle, the BMS stabilises and transmit cutouts stop.

Bar indicator showing one fewer bar than expected after swapping the pack

The VX-D281 uses a simple voltage-threshold bar indicator — it reads the pack's resting voltage against fixed cutpoints to display charge level. A new cell at storage voltage sits below the top threshold, so the radio correctly displays three bars instead of four. This is not a capacity defect. Charge the pack fully in the dock until the dock LED goes solid green, then insert into the radio — the indicator will show four bars at 8.4V resting voltage.