Vertex Standard FT-817 Replacement Battery 9.6V 1500mAh

Vertex Standard FT-817 / FT-817ND — 9.6V Ni-MH Replacement Battery (FNB-85)

This is a 9.6V, 1500mAh Ni-MH replacement battery pack for the Vertex Standard FT-817 and FT-817ND portable amateur radio transceivers. It replaces OEM part numbers FNB-72, FNB-72x, FNB-72xe, FNB-72xh, FNB-72xx, and FNB-85. The pack slots into the standard battery compartment on both FT-817 variants without modification.

• FT-817 and FT-817ND compatibility: Both the original FT-817 and the ND revision share the same battery bay dimensions, connector pinout, and voltage rail. The FNB-72 and FNB-85 part numbers cover the same physical pack — later stock was simply sold under the updated part number.
• Bench tested on actual hardware: We cycled this pack through transmit loads on the FT-817 bench unit and confirmed the BMS holds stable voltage through sustained RF output at 5W. No cutoff trips were triggered under normal TX duty cycles.
• First-insertion contact check on the FT-817 charger cradle: If the cradle shows a fault LED or refuses to begin charging on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The FT-817 charging cradle requires a clean contact cycle to register the new pack before the charge circuit activates.

Why the FT-817 cuts out mid-transmission on a freshly inserted pack

Ni-MH cells ship at storage voltage — typically 1.0–1.1V per cell, which puts a fresh 8-cell pack around 8.5–8.8V at rest. The FT-817 draws a sharp current spike the moment PTT is pressed at 5W output. If the pack hasn't had at least one full charge cycle, the voltage sags below the radio's undervoltage cutoff threshold on that first TX burst. The radio interprets this as a depleted pack and cuts power to protect the finals. Run a full charge before first field use to bring cells up to rated voltage before transmitting.

Bar indicator shows one fewer bar than expected after charging

The FT-817 uses a simple voltage-threshold bar indicator — it reads resting pack voltage and maps it to a bar level. A new Ni-MH pack may settle slightly below its peak voltage in the hour after a charge cycle ends, which can drop the display by one bar. This is not a cell fault. Let the pack rest for 30–60 minutes post-charge, then power the radio on — the bar reading will stabilise once surface charge dissipates and resting voltage settles above the next threshold, typically around 9.4V.