Yaesu FNB-V106 VX-231 Replacement Battery 7.2V 1200mAh

Yaesu VX-231 / VX-228 Series — 7.2V Ni-MH Replacement Battery (FNB-V106)

This is a 7.2V, 1200mAh Ni-MH replacement battery pack for the Yaesu VX-228, VX-230, VX-231, and VX-231L handheld transceivers. It replaces OEM part numbers FNB-V106 and AAG57X002. Capacity figure is taken directly from product data — 8.64Wh total energy.

• VX-228 / VX-230 / VX-231 / VX-231L compatibility: All four models share the same battery bay dimensions, 7.2V nominal rail, and contact arrangement. The BMS handshake protocol is identical across this platform, so one pack fits the full range without modification.
• Bench tested on actual hardware: We cycled this pack on a VX-231 under PTT transmit loads. The BMS held stable across repeated transmit bursts and did not trip on the initial current spike at key-up. Contact voltage at full charge measured within spec for dock acceptance.
• First insertion into the charger dock: 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 VX-series charger dock requires a clean contact cycle to register the new pack's BMS signal before charging begins.

Why the VX-231 cuts out mid-transmission on a freshly inserted battery

Ni-MH cells shipped from storage typically sit at 1.0–1.1V per cell, which puts a 6-cell pack below 7.0V total. When PTT is pressed, the transmit current draw causes an immediate voltage sag. If the pack voltage drops below the BMS cutoff threshold under that load, the radio shuts off before the transmission completes. This is not a faulty pack — it is a storage-voltage cell under high demand. Running one full charge cycle before field use brings each cell to 1.2V nominal and eliminates the sag-induced cutoff.

Bar indicator showing one fewer bar than expected after a full charge

The VX-231 uses a simple voltage-threshold bar indicator — it reads pack voltage in real time and maps it to bar levels. A new Ni-MH pack that has only completed one partial charge cycle may rest at 7.1–7.2V rather than the full 7.6V a well-conditioned pack holds. That lower resting voltage pushes the reading one threshold below what the indicator expects. Charge the pack a second time immediately after the first cycle completes — resting voltage after the second charge should read 7.4V or above, and the bar display will update accordingly.