voltage question

nick46and2
10+ year member

Junior Member
hey guys, quick question from an electrical retard...i was reading up on a few amps and they had a certain power output for (bare with me here cant remember the exact #'s) i think a 13.5 volt car and then higher outputs for say a 14.4 volt (again dont remember exact #'s) for the same amp. my question is is your voltage power from your battery, alternator, both, or something else i might be missing, and how do you know what the voltage is on your car?

 
Your alternator is supposed to run your car. With all accessories (A/C, power windows etc....) operating, the load should not exceed the output of the alternator. Additional items like aftermarket driving lights, amplifiers and such were not calculated into the design of the vehicle. These things will sporatically exceed the limits of the alternator and that's when the extra power that is needed is drawn from the battery. The 13.5 and 14.4 are the common output voltages in American cars. 13.5 GM 14.4 Ford. I'm not sure of the imports but they are within that range. If you are wondering what your particular vehicle is running at, simply use your digital volt meter and connect it to your battery while your car is running.

 
The numbers usually quoted in amp specs are either 12V (running from the battery, engine off), or 14-something (running off the alternator, engine running). Some amps have different power output depending on the voltage supplied by the system. Some amps have internally regulated circuits that put the same power out regardless.

 
I'd measure your actual voltage with a multimeter. Alternators have regulators on them, and not all are regulated at the same voltage. My Volvo only does 12.9 volts, max, with just the default load.

 
A lot of amps are also made to work with higher voltage, with awe-inspiring results, you can get a dc/dc converter for that, but it's a hell of a power drain.... I think..

 
Enziee,Wouldnt that be 13.8V and 14.4V //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif
I drive and have driven GM (Chevy) since my first days of possessing a license. I am fairly confident that it is 13.5 after everything stabilizes. //content.invisioncic.com/y282845/emoticons/moon.gif.9d317aec3339ffe7fde0638df52c628a.gif

 
Mmm, 15 volts with everything? that isnt too good.... 14.4 is optimal for stock wiring and stock electrical components. If your getting more than 15 your regulator might be crapped out. Unless you purposly have a 16/18 volt reg?

 
LOL,i get 11V with everything on.

Yeah, i need a new alt, i know.

With 15V your awlking on thin ice, 15.5V is where every thing starts to burn up
Thin ice is cool //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

I was a little concerned too at first, but it's all been running fine now for close to a year.

Besides - I've heard you can go as high as 17v before there are going to be problems. It just depends on who you talk to.

With everything off it will idle as high as 15.3-15.4.

Incidentally, when I first replaced the original 75A alt - it was with a different 110A. When I installed it I eventually figured out that it had a blown regulator. As soon as I started the car the voltage would climb - about a volt a second. It got as high as 18v once before I got it turned off. After watching it go to 17v a couple more times I removed it and found another one (the one I have now).

 
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nick46and2

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