do i need a new alternator or battery???

[andrew N.]

on my way to the track my digital volotometer was going nuts and blinking, its usually at 13.5 or so. but it fell to the 11's and even 10's on the highway, even at about 2500rpms.

then i ran my worst time of the season.

[DigitalBee]

I don't know if our problems are related or not, but I am having a similar problem. My voltage meter fluxuates badly at idle, and when I have my car off, and on accessary for the stereo, the voltage meter shows way below 12v and this is just after I kill the motor without anything on.

I recently replaced the battery about 3 months ago. According to my battery/alt tester, the alt puts out between 12 and 13.5v, it fluxuates back and forth.

[DigitalBee]

I don't know if our problems are related or not, but I am having a similar problem. My voltage meter fluxuates badly at idle, and when I have my car off, and on accessary for the stereo, the voltage meter shows way below 12v and this is just after I kill the motor without anything on.

I recently replaced the battery about 3 months ago. According to my battery/alt tester, the alt puts out between 12 and 13.5v, it fluxuates back and forth.

[SweetNsLowV6]

my car is doing that also, but the interior dome lights and the headlights are flickering as well, its almost like i have strobe lights, i think that one of the diodes in the alternator is going bad

[MTMike]

It could be one or the other. A bad battery not taking a charge will cause simliar problems. More likely than not though, it's the alternator, or something in it. It could be the voltage regulator inside the alt - that's the most common thing to go out on alts.

-Mike

[andrew N.]

autozone tested mine for free, its my alternator like i thought.

[Big Tymer]

to tell if ur alternator is bad..... ro the battery.... start the car.... whiel car is running... unhook the positive cable going to the battery. if car shuts off... its ur alternator.. if car stays on.. its the battery. :)

[Jhonathan]

if the lights flicker while the car is running its almost surely the alternator, the main reason i know, ive gone through like 5 alternators so im gettin pretty good at telling when they are about to die [img]smile.gif[/img]

[MTMike]

<blockquote>quote:</font><hr>Originally posted by Big Tymer:
to tell if ur alternator is bad..... ro the battery.... start the car.... whiel car is running... unhook the positive cable going to the battery. if car shuts off... its ur alternator.. if car stays on.. its the battery. :)<hr></blockquote>

That is a good way to check... however, never remove the positive side of the battery first Always remove the negative side first in a negative ground system :D