Yaesu VX-820 FNB-V86LI Replacement Battery 7.4V 2200mAh

Yaesu VX-820 / VX-821 / VX-824 / VX-829 Series — 7.4V Li-ion Replacement Battery (FNB-V86LI)

This is a 7.4V, 2200mAh (16.28Wh) lithium-ion battery for the Yaesu VX-820, VX-821, VX-824, and VX-829 handheld transceivers. It replaces OEM part numbers FNB-V86LI and FNB-V87LI. The battery slots directly into the radio's battery bay and connects via the standard Vertex contact strip.

• VX-820 series platform fit: The VX-820, VX-821, VX-824, and VX-829 share the same battery bay dimensions, voltage rail, and contact pinout. A single pack covers all four models because the BMS handshake threshold and connector layout are identical across the series.
• Bench tested on actual hardware: We cycled this pack on a VX-820 through repeated PTT transmit bursts. The BMS held the voltage rail stable under the transmit current spike and recovered cleanly between transmissions without triggering overcurrent cutoff.
• First insertion contact cycle: 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 platform requires a clean contact cycle to recognise the new BMS and begin charging.

Why the VX-820 cuts out mid-transmission on a freshly inserted battery

Replacement packs ship at storage voltage — typically around 3.7V per cell, or roughly 7.4V combined. That's at the lower edge of the VX-820's acceptable input range. When PTT is pressed, transmit draw spikes sharply and the BMS may trip overcurrent protection before the cells have been conditioned through a full charge cycle. This isn't a defective pack — it's the BMS doing its job at a low state of charge. Charge the battery fully before first field use; the cutout behaviour stops once the cells are at operating voltage.

Bar indicator showing one fewer bar than expected on a new FNB-V86LI

The VX-820 uses a simple voltage-threshold bar indicator — each bar corresponds to a voltage band, not a percentage from a fuel gauge chip. A new pack at storage voltage reads lower than a fully charged cell, so the radio displays one fewer bar than it will after a full charge. This is normal behaviour for any new lithium-ion pack. Charge the battery completely in the dock and confirm the indicator reads full before drawing conclusions about pack capacity.