Voltage making difference

[danz24 10+ year member]

I have a problem with my alternator. For some reason it idles at 12v now and when I hit the gas my voltage can only reach maximum of 13.9v. My question is that will this lower voltage mean that the amp will draw lesser power? And if it does will there be an audible difference or even a difference on the TL??

I have about 2K rms on it, sub amp is USAMPS MD2D older version.

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[Side Show 10+ year member]

get a drycell battery with a really good cca rating, should be able to hear the difference once installed

 

[danz24 10+ year member]

Thanks for the help but that dosent answer the question.

 

[jrwalte 10+ year member]

Depends. An amplifier will draw more amperes in order to maintain the same wattage at the lower voltage as you were pushing at the higher voltage, providing you weren't pushing the amp to its limits. If the amp is at it's RMS limits, then the more voltage the more wattage output (I suspect this is because an amp has a max amperes limit it can handle in conversion to AC?). If your amp isn't at its limit and if your battery can't provide the extra amperage (your alternator already can't because that's why the voltage is dropping to begin with), then yes, it would be affected.

Does your voltage idle at 12ish with the music off or low or only when it's loud?

 

[danz24 10+ year member]

Idles at 12v with all electronics off.

 

[jrwalte 10+ year member]

Idles at 12v with all electronics off.

That's not good. This may be an indicator that your alternator is going bad. If your resting voltage isn't higher than 13, then the battery isn't getting a good charge and probably evident that your alt is not putting out the amperage it should be. Time for a HO alt //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[danz24 10+ year member]

lol it IS HO alt. So with my situation is the lower voltage affecting my performance noticably?

 

[01 S 10 10+ year member]

your HO alt might be bad... dont worry about the performance of your system right now, your vehicle might not make it another 20 miles if your alt dies.

 

[Tragic00 10+ year member]

your HO alt might be bad... dont worry about the performance of your system right now, your vehicle might not make it another 20 miles if your alt dies.

x2

My GM alt idles at 14.5v-14.8v and seeing as it is only a 125amp, I would guess you have a bigger problem on your hands over performance.

 

[danz24 10+ year member]

It charges though, it does 13.9 when I hit the gas... But of course I will replace it, just saving $ atm

 

[jrwalte 10+ year member]

AH. Your HO alt may be fine. Your pulley may be too large and your alt isn't getting the rpm it needs to create decent amperage at your car's idle. Some HO alts won't even start giving amperage until a certain internal RPM is reached. It's a common issue with HO alts. I'd contact the company you bought the alt from and talk to them about a smaller pulley. You want to make sure you get one that they support or you could over rpm your alt and damage it.

 

[01 S 10 10+ year member]

but didnt this problem just start happening? or has it happened the whole time the H.O. alt was installed?

 

[jrwalte 10+ year member]

but didnt this problem just start happening? or has it happened the whole time the H.O. alt was installed?

Ah, true. If it originally was OK with the HO alt and has just started idling at 12 now then I'd call about a warranty //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif