Vertex Standard FNB-41 Compatible Battery 9.6V 1000mAh

Vertex Standard FT-10 / FT-40 Series — 9.6V Ni-MH Replacement Battery (FNB-41)

This 9.6V, 1000mAh Ni-MH pack replaces the OEM FNB-41 and FNB-42 batteries in Vertex Standard portable two-way radios. It fits the FT-10, FT-10R, FT-40, and FT-40R among other models in the series. Voltage, connector, and BMS handshake all match the original specification.

• FT-10 / FT-40 platform fit: These models share the same battery bay geometry, 9.6V rail, and multi-pin contact arrangement. The FNB-41 and FNB-42 are cross-compatible across this group because Vertex Standard held the same physical and electrical standard across both the R and non-R variants.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on an FT-10 body. The BMS accepted the dock charge sequence without fault, and transmit current draw on PTT press stayed within the rated threshold throughout the test.
• Contact strip seating on first insertion: If the 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 before it will accept the new BMS handshake and begin charging.

Why the FT-10 cuts out mid-transmission on a fresh battery

A new Ni-MH cell ships at storage voltage — typically around 1.0V per cell, which puts this 8-cell pack near 8.0V rather than its nominal 9.6V. When PTT is pressed, transmit current spikes sharply. If the pack hasn't completed at least one full charge cycle, that voltage sag can trip the radio's undervoltage protection and kill the transmission. Run a full charge before the first field use. After one complete cycle, the cells stabilise and the cutout behaviour stops.

Bar indicator showing one fewer bar than expected after charging

The FT-10 and FT-40 read battery level from a simple voltage-threshold circuit — there is no fuel gauge chip recalibrating itself. If the bar display looks short after charging, the pack likely hasn't reached peak voltage yet from a storage state. Let the dock complete a full, uninterrupted charge cycle. Once the pack peaks above 11.0V at rest, the bar indicator will align with what the radio expects to see.