how do i know if an alt is bad

[chevydude361 10+ year member]

well my car battery is not holdin a charge and my lights inside dimm so would a bad alt be the cause of this and how do i know if its bad or not

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[bibby 5,000+ posts]

how do i know if an alt is bad?

 

 

Take it to AutoZone, and have them test your electrical.

 

[chevydude361 10+ year member]

ok so i take it off the car and take it to them so they can test it and how much would it cost

 

[phyphoestilic 5,000+ posts]

u can do it that way. But most autozones also have a tester with it in the car. They should do it for free

 

[chevydude361 10+ year member]

ok cus i cant run my car right now

 

[yne721 10+ year member]

ok cus i cant run my car right now

i bet buying a cheapie battery just to get it up to autozone would be less of a hassle than taking out your alt, unless your alt is easily accessible..

 

[Prowler573 5,000+ posts]

Yes, Auto Zone or Pep Boys or Advance Auto (whichever is more convenient for you) will all test alternators and starters and batteries free of charge.

I'm sure NAPA will test them as well but as I have no direct experience with them I do not know if they would charge for the process or not.

I do know the three parts houses I mentioned at the beginning of this post do it free of charge. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[chevydude361 10+ year member]

ok thanks guys

 

[corto 10+ year member]

what about taking a screw driver and directly on the back and touch it to see if its lost its magnet

 

[corto 10+ year member]

opps

 

[corto 10+ year member]

what about taking a screw driver and directly on the back and touch it to see if its lost its magnet strength? or dissconnect negative batteryand if car stalls its the alt?

 

[neonrt 10+ year member]

an easy way to tell if its dead in your own driveway is to have the car running, and remove the positive from your batt. if the alt is completely screwed your car should stall out due to not having enough power to run anything.

 

[mlstrass 5,000+ posts]

how about using a DMM and testing voltage at idle??? If it's lower than the rated output alt is probably going out. Also make sure the belt isn't worn/slipping as that will cause the alt to not have proper output.

Also could be your batt taking a crap or bad/corroded POS/NEG wire. Gonna have to get your hands dirty and start troubleshooting...

 

[aaron7114 10+ year member]

Also havin similar problems...my voltage used to run around 14.5 volts. But now i hardly ever see it 14+...its usually running 13.5 or so. Got a lifetime warranty on the alt from o riellys.

 

[Twistid 5,000+ posts]

turn on the car, pour a bucket of water onto the alternator... if nothing happens it doesnt work