How much should my voltage flucuate?

[ghart999 10+ year member]

Got an excessive amperage 200A alt a few weeks ago and added a voltmeter at the same time.

Voltage starts out at 14.8V where i start the car and jumps down as low as 12 at idle but maintains around 13.8 when driving aroudn town and back to 14.2-14.4 at highway speeds. Is this typical?

The 12V at idle seems a bit low to me.

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[jacka 10+ year member]

wow.. 12 does seem pretty low. the lowest im at with the engine on is ~13.6. could it be the voltage regulator?

 

[ghart999 10+ year member]

OK I will check to find out if my voltage reg is messed up.

 

[Ali1 10+ year member]

dude, i just got a 200amp EA alternator and it's doing the same thing. It idles at 12.2v... tested it yesterday .When I rev the engine @ 1100rpm, it goes to 13.8v. Anything higher than 1500rpm, it will charge at 14.0v. It's confusing a few days ago i was getting different numbers......

 

[darren700 10+ year member]

yup i got the exact same problem with my 160a alt

 

[ghart999 10+ year member]

cool deal on the smaller pulley

 

[iamamp3pimp 5,000+ posts]

cool deal on the smaller pulley

how is it?