Vertex Standard V318 Compatible Battery FNB-V165 7.4V 1650mAh

Vertex Standard V318 / VZ Series — 7.4V Li-ion Replacement Battery (FNB-V165)

This 7.4V, 1650mAh Li-ion battery replaces the FNB-V165 and FNB-V165LI packs used in the Vertex Standard V318, VZ-10, VZ-12, and VZ-18 portable two-way radios. It fits the same physical footprint and connector as the original, with a BMS matched to the voltage thresholds these radios expect. Capacity is drawn from product data — 1650mAh / 12.21Wh.

• V318 and VZ series compatibility: The V318, VZ-10, VZ-12, and VZ-18 share the same battery bay dimensions, contact layout, and 7.4V nominal voltage rail. The BMS in this pack communicates the same charge-acceptance signal the dock reads during the initial handshake, so all four models accept the pack without dock errors on insertion.
• Bench tested on actual hardware: We cycled this pack through PTT transmit loads on the bench and confirmed the BMS holds the voltage rail stable through the transmit current spike. The pack did not trip overcurrent cutoff under sustained key-up sequences.
• First insertion on the dock: If the charger 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 dock requires a clean contact cycle to complete the BMS handshake before charging begins.

Why the V318 cuts out mid-transmission on a freshly inserted FNB-V165

New Li-ion cells ship at storage voltage — typically 3.6–3.7V per cell, giving a pack voltage around 7.2–7.4V. The V318 draws a sharp current spike the moment PTT is pressed to power the RF stage. If the pack hasn't completed at least one full charge cycle, that spike can pull the pack voltage low enough to trip the BMS overcurrent protection, killing the transmission mid-key. The fix is straightforward: charge the pack fully before the first use. One full charge brings both cells to 4.2V each, giving the BMS enough headroom to absorb the transmit surge without cutting off.

Bar indicator showing one fewer bar than expected after installing the FNB-V165

The V318 and VZ series use voltage-threshold bar indicators — the radio reads pack voltage and maps it to a bar count, with no fuel gauge chip involved. A new pack at storage voltage reads lower than a fully charged pack, so the radio displays one bar fewer than it will after charging. This is not a faulty cell or a capacity mismatch. Charge the pack fully; once both cells reach 4.2V the indicator will move to the expected bar level. If it still reads low after a full charge, check that the dock contacts are clean and making firm contact with the gold strip on the pack.