alt. or battery goin bad

[30hrtz 10+ year member]

I started having voltage issues a couple days ago.Have a constant low humming or whining sound coming from under the hood,sounds like the alt,not sure.The meters reading 14.5 at the battery with the truck running and 12.4 on the battery with truck off.whenever I first start the truck the volt guage is reading about 12v and gradually over a couple minutes gets up to 14.the battery is 3 years old...and i cannot play my system with any kind of volume without severe dropage of the volt guage.big 3 has been done,18months ago w/4ga. and total power of my setup is around 1000 watts.never had an issue with volts dropping until this week.thanks for any advice.(and getting an H.O. alt is out of the question)

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[mapolley07 10+ year member]

take your batt to the closest autozone and have them test it, they do it for free. they can also test your alternator, but only if it matches up with an alternator they sell, i.e. factory alt

 

[Linkz 10+ year member]

I would say you have a bad alt. It may be reduced to only being able to take a small load.

 

[30hrtz 10+ year member]

we do have an autozone close by,I ll go tomorrow and have them check the alt.is is a factory alt. on a 1995 gmc sonoma,not sure of the output.

 

[Trez0r 10+ year member]

Wouldnt hurt to upgrade to some 1 guage wire.

mbyiduno.?

might make a diff

 

[lorideslo 10+ year member]

Wouldnt hurt to upgrade to some 1 guage wire.
mbyiduno.?

might make a diff

x2

 

[30hrtz 10+ year member]

well, quick update,went to autozone and they said its a bad diode in alt. well ifigured they say that,so i got one but havent put it on yet,will do this afternoon.as far as the 1ga wire goes,i may do that someday,but it wouldnt help here as far as my present situation goes.on the way to the parts store,i turned on my lights and the volts started dropping on the guage,so i will put the new alt on,then see how it is.if its still not right,i got an everstart maxx battery from walmart which has a 3year free exchange so i can take it back and get a new one,so i'll keep yall updated,like i said,i ll put the alt on this afternoon and see.

 

[30hrtz 10+ year member]

o.k. changed alt, and all is well.