Vertex Standard FT-23R 12V Ni-MH Replacement Battery FNB-10

Vertex Standard FT-23R / FT-33R / FT-73R / FT-411 Series — 12V Ni-MH Replacement Battery (FNB-17)

This is a 12V, 1000mAh Ni-MH replacement battery pack for Vertex Standard portable handheld transceivers. It cross-references OEM part numbers FNB-10, FNB-10H, FNB-12, FNB-12H, FNB-14, FNB-14H, FNB-17, and FNB-17H. Compatible models include the FT-23R, FT-33R, FT-73R, and FT-411, among others.

• FT-23R / FT-33R / FT-73R / FT-411 compatibility: These models share the same 12V battery architecture, connector pinout, and BMS handshake protocol — one pack form factor covers the full range without modification.
• Bench tested on actual hardware: We cycled this pack through transmit loads on the FT-23R. The BMS handled PTT current spikes without tripping, and voltage held steady across sustained RF output bursts.
• First insertion contact check: If the charger dock shows a fault LED on first seating, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. This platform requires a clean contact cycle to complete the BMS handshake before charging begins.

Why the FT-23R cuts out mid-transmission on a freshly installed battery

A new Ni-MH cell ships at storage voltage — typically around 1.2V per cell, with the full 12V pack sitting closer to 11.8V. When PTT is pressed, transmit current spikes sharply and voltage sags under load. If the BMS reads that sag as a fault condition, it trips and drops the radio mid-transmission. A full charge cycle before first use brings cell voltage to operating level and closes the gap between open-circuit and under-load voltage, preventing false BMS trips during TX.

Bar indicator showing one fewer bar than expected after pack swap

The FT-23R uses a simple voltage-threshold bar indicator — each bar maps to a voltage band, not a fuel gauge calculation. A new pack at storage voltage reads low on that scale and displays one bar fewer than actual capacity. This is not a fault. Charge the pack fully in the dock until the charger LED goes solid green, then power on the radio — the indicator will reflect the correct charge state at 12V loaded.