JonB

iTrader: (3)

It's in my gf's car. The battery is less than 1 year old. It was dead monday she had it jumped and it ran and started fine until last night she again had it jumped and it was fine again this moring. I checked the voltage at the battery this morning and it was 12.4-12.5 and then checked it agian after a short drive and it was 13.8-13.9 with the a/c off. Not sure if either of those are good numbers or bad. She also had autozone check and they said both the battery and alt were fine. Assuming there right which im not assuming the only other thing would be a short/draw from somewhere. Anyone have any expert advise on narrowing my options down. Also for awhile now her security light has been coming on randomly not sure if its related or not.

Thanks
Jon

I got a few more numbers with the car at full load stereo, a/c fan and cooling fans with the battery's negeative cable unhooking the battery was like 12.8 and with using a different ground(the strut bolts) and the postive battery it was like 13.3-13.4.

waiting2bl33d

i think your alt is going bad...the reason that it didn't show bad is because its not under the fail range yet.

JonB

iTrader: (3)

I'm kinda thinking its the alt to because she only drives it maybe a mile to work and its probably not charging good in that short trip. Anyone know what kind of voltage the alt should be putting out. I don't want to replace it untill I know that it's indeed that alt. I had it checked a second time at a different autozone and they also said both battery and alt are fine. I cleaned up as many ground wire's I could find and checked for stripped or burt wires. I'm totally lost and im stuck driving here Z28 untill its fixed not that her Z is bad but I like mine much more.

Wyoming T/A

iTrader: (1)

alt should put put 14.2 to 15.5 volts at 2500 rpm.if in that range it should be ok.if the battery was low it will take several hrs to charge.if you have a trickle charger put it on for 24 hrs

joshp14

iTrader: (5)

Actually it depends on the car manufacturer, some put out 13, some 15, use the 13-16 volt range at 1500-2000 RPM.