About this replacement
Motorola EVX-C59 / EVX-C51 Series — 7.4V Li-ion Replacement Battery (FNB-V146LI)
This is a 7.4V, 1800mAh Li-ion battery for the Motorola EVX-C59, MagOne EVX-C59, EVX-C51, and MagOne EVX-C51 portable digital two-way radios. It matches the OEM form factor and connector of the FNB-V146LI pack. Capacity is 1800mAh (13.32Wh) — taken from product data, not estimated.
- EVX-C59 and EVX-C51 platform fit: Both the standard EVX and MagOne variants share the same battery bay dimensions, contact layout, and BMS handshake protocol — which is why one pack covers all four listed models. Swapping between variants does not require any configuration change.
- Bench tested on actual hardware: We ran this pack in an EVX-C59 dock and confirmed the BMS completed its handshake on first insertion. Charge acceptance was normal, and the radio recognised the pack without any fault state.
- First insertion on the Vertex/Motorola dock: If the dock shows a fault LED on first insertion, remove the battery, wipe the gold contact strip with a dry cloth, and reseat firmly. The dock requires a clean contact cycle to accept the new BMS handshake before charging begins.
EVX-C59 cuts out mid-transmission on a freshly inserted pack
The EVX-C59 draws a sharp current spike the moment PTT is pressed — transmit load can hit 2–3A in under 100 milliseconds. If the BMS on a new pack is still in storage-state, it may read this spike as an overcurrent fault and cut output before the radio completes the transmission. This is not a faulty battery. Let the pack charge fully in the dock before first use, then key up briefly a few times to let the BMS register normal transmit load. After two or three PTT cycles the BMS recalibrates its overcurrent threshold and the cutout stops.
Bar indicator shows one fewer bar than expected after a full charge
New Li-ion cells ship at storage voltage — typically around 3.7–3.8V per cell, not the 4.2V per cell they reach after a full charge cycle. The EVX-C59 reads battery level from a simple voltage-threshold bar indicator, so a pack that just arrived will show one bar low even if it was never used. Run one complete charge cycle in the dock until the indicator goes green, then reinsert the battery. At full charge the radio should display the expected bar level.