I was wondering if there is any advantage or difference in running a radio off of 13.8 volts as opposed to 12 volts, because I have a friend who says that radios will only work properly with 13.8 volts and that 12 volts is not enough power. But I have ran the radio off of just a 12v gel battery and the radio seemed to work just fine with only 12.6volts from the battery(dropped to 11.9 on voice peaks running 100watts and lights on radio dimmed), when I hooked that same radio up to a 13.8volt power supply the only difference was that the lights didn't dim, and I seemed to be getting out exactly the same as I was when I running it off of 12volts. I also tried this with another radio and I did not notice any difference whatsoever between the 12volt battery and 13.8volt power supply (power output was the same and the lights did not dim). So my question is does the radio care if you run it off of 12volts as opposed to 13.8volts? Is it any better running off of 13.8volts rather than 12volts? Can it damage anything if you supply it with 1.8volts lower or higher than the rated voltage of the radio? If the extra 1.8 volts does not make a difference then why do they make power supplies that put out 13.8volts instead of 12volts(many 12volt power supplies actually put out 13.8volts NOT 12volts)? Is it so you can use them to charge the 12volt batteries (because you need more than 12volts to charge a 12volt battery and the battery charger I have actually puts out anywhere between 12.9 and 16volts depending on charge state of the battery)? It seems like using a 12volt 20A power supply would be more efficient than using a 13.8v 20A because it will use slightly less wattage due to a lower output voltage at the same current (assuming they have the same efficiency and are both putting out the same amount of current), which would result in a (slightly) cheaper electric bill when operating the radios. Have any of you noticed any difference between the two voltages?