Yaesu FNB-57 Replacement Battery 7.4V 2600mAh Li-ion

Yaesu FT-60 / FT-60R Series — 7.4V Li-ion Replacement Battery (FNB-83)

This is a 7.4V, 2600mAh lithium-ion battery for the Yaesu FT-60 and FT-60R handheld transceivers. It replaces OEM packs FNB-57, FNB-64, FNB-64H, FNB-83, FNB-83H, FNB-V57, FNB-V57H, and FNB-V67Li. The cell format, connector, and BMS pinout match the FT-60 platform directly.

• FT-60 and FT-60R platform fit: Both models share the same battery bay dimensions, locking tab geometry, and three-pin contact layout. The BMS on this pack uses the same voltage thresholds the FT-60 firmware expects — no mode limitations or charger rejection caused by a mismatched protection circuit.
• Bench tested on actual hardware: We cycled this pack on an FT-60R using a standard VAC-1 wall charger and monitored BMS behaviour through charge and a simulated PTT transmit load. The protection circuit held steady across repeated high-current draw spikes without tripping into lockout.
• First charge on the FT-60 dock: New cells ship at storage voltage, typically around 3.6–3.7V per cell. If the FT-60 desk charger shows a fault or blinking LED on first insertion, remove the pack, wipe the contact strip with a dry cloth, and reseat it firmly — the charger requires a clean contact cycle to register the BMS before it begins the charge sequence.

Why the FT-60R cuts out mid-transmission on a fresh pack

The FT-60R draws a spike of current the moment PTT is pressed — FM transmit at full power pulls significantly more current than receive or standby. If the BMS interprets that spike as an overcurrent fault, it trips the protection circuit and cuts power before the transmission completes. This usually happens when the pack has just come off charge and the BMS hasn't completed its initial handshake cycle with the radio. Fully cycling the charger and letting the pack reach 8.3–8.4V before first use resolves this in most cases.

Bar indicator showing one fewer bar than expected after charging

The FT-60 uses voltage-threshold bar indicators — each bar corresponds to a voltage band, not a fuel gauge reading. A new pack charged to 8.2V may display one fewer bar than a fully charged original pack at 8.4V. This is a threshold display behaviour, not a cell fault. Run two full charge cycles on the VAC-1 or equivalent charger, confirm the pack reaches at least 8.3V on a multimeter, and the bar reading will align correctly.