About this replacement
Vertex Standard VX-160 / VX-410 Series — 7.4V Li-ion Replacement Battery (FNB-V126Li)
This 7.4V, 2600mAh Li-ion battery replaces the FNB-V126Li in Vertex Standard portable two-way radios. It fits the VX-160, VX-180, VX-210A, VX-410, and more than ten additional models in this series. Voltage and connector match the original pack exactly.
- VX-160 / VX-410 platform compatibility: These models share a common 7.4V power rail, identical latch geometry, and the same BMS handshake protocol — which is why one pack covers the full lineup. The dock communicates with the BMS over the contact strip before accepting a charge cycle.
- Bench tested on actual hardware: We cycled this pack through full charge and discharge on a VX-series dock. The BMS responded correctly to transmit-current spikes during PTT testing, and charge termination triggered at the expected voltage without fault codes.
- First insertion into the dock: If the charger shows a fault LED on first insertion, remove the pack and wipe the gold contact strip with a dry cloth. The VX-series dock requires a clean contact cycle to register the BMS handshake before charging will begin. Reseat firmly and the LED should clear within 10 seconds.
Why the VX-160 cuts out mid-transmission on a freshly installed pack
During PTT, a VX-160 draws a sharp transmit current — typically 1.5A to 2A — that spikes above the steady receive current. If the replacement pack is at storage voltage (around 3.7V per cell), the BMS may interpret that spike as an overcurrent event and trip the protection circuit momentarily. This causes the radio to drop audio or cut the transmission short. The fix is straightforward: seat the pack in the dock and run a full charge before first use in the field. After one complete charge cycle, the BMS recalibrates its overcurrent threshold to operating voltage and the dropout stops.
Bar indicator showing one fewer bar than expected on a new FNB-V126Li
The VX-series bar indicator reads voltage thresholds directly — it does not track charge history. A new cell shipped at storage voltage reads lower than a fully charged pack, so the radio displays one bar fewer than it will once charged. This is not a fault with the cell. Charge the pack fully before reading the indicator — a full charge brings each cell to approximately 4.2V, and the display should reflect three or four bars depending on your specific model's threshold mapping.