When installing a mobile radio in a vehicle, there are some considerations that need to be made in terms of powering the radio. Aside from where to get the power from, there is the decision that has to be made as to when you want the radio to be able to be turned on.

Generally, the radio will either be powered direct to the battery (or some power source that has power all the time) or powered through a lead that only has power when the ignition is on. There are benefits and drawbacks to both options.

If you have the radio supplied directly from the battery or another source that always has power, you will be able to use the radio without having to leave the vehicle on. This can be beneficial if you want to use a radio in your vehicle as a digipeater or use the cross-band repeat function on your radio. If the radio is powered direct, you will be able to leave the radio on when the vehicle is off, lock the door and walk away, bringing the keys with you. The drawback to this is that there is the chance that you will forget to turn the radio off when you are done using it or done driving and next time you go to your vehicle, the battery will be dead. Another drawback to this is that you have to manually turn the radio on and off every time you get in and out of your vehicle.

Having the radio power switched through the ignition can overcome these drawbacks of direct power. If you have it switched through the ignition, the radio will only have power when the ignition is on. Generally, when the ignition is on the vehicle is running (the vast majority of the time anyway) and the alternator is producing more electricity. This eliminates any worry of running the battery down. Also, with this setup, if you don’t manually turn the radio off, it will shut off when it loses power (you turn the ignition off) and turn back on when there is power again (you turn the ignition on) eliminating the need for you to turn the radio on and off separately.

The main drawbacks of having the radio powered through at switched circuit are that you cannot as easily take advantages of the features of the radio that you would be able to through direct power.

As a happy medium, I think that when I install the radios in my vehicle, I may have two paths for the power to get to the radios. One of those paths will be switched through the ignition and would be the path that would be used on a day to day basis. I will be able to jump in and go with no extra buttons or switches to mess with and will not forget to turn the radio on or off. The other path will consist of a direct power type setup that will include a switch that I can then put under or at the bottom of the dash. This switch will then be able to be powered on if I am in a situation where I want my vehicle to act as a digipeater or use the cross-band repeat function of my radio. I will then be able to power the radios by either turning on the ignition or flipping the additional switch.