from motorolas pdf...
Red to Battery, Black to Ground, Yellow to Fuse panel either power all the time or Switched according to the diagram both red and yellow on a 5 amp fuse after power connection points..
The yellow wire controls whether or not the APX VA radio battery charger will be “live” at all times.
Consider the functionality and vehicle battery drain current below during installation.
Standard Wiring to Vehicle Switched A+ – Charging OFF with Vehicle OFF
For installations where the radio may be left in the APX VA with the vehicle’s ignition switched
OFF and minimal vehicle battery drain current is important, the standard wiring connection
of the yellow wire to vehicle switched A+ will disable charging.
Optional Wiring to Vehicle A+ – Charging ON with Vehicle OFF
When the radio is left in the APX VA for charging with the vehicle’s ignition switched OFF, the
optional wiring connection of the yellow wire to always-live vehicle (A+) will keep the charger ON.
When the operator takes the radio from the APX VA, low vehicle battery drain current will occur.
PDF is too large to post so heres the link to the pdf
https://www.motorolasolutions.com/c...s/chargers/APX_VehicularAdapter_UserGuide.pdf
Page 22 and 23 deal with power wiring