Vertex Standard EVX-231 Replacement Battery 7.4V 2600mAh Li-ion

Vertex Standard EVX-231 / EVX-530 Series — 7.4V Li-ion Replacement Battery (FNB-V134Li)

This 7.4V, 2600mAh Li-ion battery replaces OEM part numbers FNB-V134Li, FNB-V136, FNB-112Li, FNB-113Li, AAJ67X001, and AAJ68X001. It fits the Vertex Standard EVX-231, EVX-261, EVX-530, EVX-531, and eight additional models in the same platform family. Voltage and capacity match OEM spec exactly.

• EVX-200 and EVX-500 platform compatibility: These two series share the same 7.4V battery bay, connector pinout, and BMS handshake protocol — which is why one pack covers both. The radio's charge management circuit reads the same pack ID from either series without modification.
• Bench tested on actual hardware: We ran this pack on an EVX-231 and EVX-530 dock. The BMS accepted the handshake on first insertion, charging initiated without fault, and PTT transmit current spikes did not trip the overcurrent threshold across repeated keying cycles.
• First insertion into the dock: If the dock shows a fault LED on first seating, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The Vertex platform requires a clean contact cycle to complete the BMS handshake before charging begins — a single wipe clears most first-insertion rejections.

Why the EVX-231 cuts out mid-transmission on a new battery

The EVX-231 draws a sharp current spike the moment PTT is pressed — RF output at full power can pull 1.5–2A in the first 100ms. If the replacement pack's BMS has a conservative overcurrent trip point, that spike can trigger a momentary cutout before the radio locks onto the channel. This is a BMS threshold issue, not a capacity issue. The fix is to cycle the pack through two or three full charge-discharge sequences so the BMS calibrates its trip point against the radio's actual load profile. After conditioning, the cutouts stop.

Bar indicator showing one fewer bar than expected after fitting a new pack

New Li-ion cells ship at storage voltage — typically 3.6–3.7V per cell, which puts the pack around 7.2V total. The EVX series maps its bar display against fixed voltage thresholds, so a pack at 7.2V reads one bar low even though the cell is healthy and nearly full. This is not a fault. Place the pack in the charger dock and run a full charge cycle to 8.4V. Once the pack reaches that voltage, the bar indicator will read correctly on the next power-up.