it has to be the alt right?

[xxxbasshead 10+ year member]

got into my car this morning and while i am pulling out of the drive way i see my voltage at 11.7 WTF. so i stopped turned off my radio and unpulged the power on my amps and drove to work. i figured i had been draining the electrical too much and the batts needed a charge. as i am driving my voltage dips down to the 10.9x and it starts to worry me. i thought maybe a fuse between the alt and the voltmeter is blown but nope there was not a blown fuse anywhere. so i take out my multimeter just now while i am on lunch and see that with my car on my front batt is at 11.5V.

it has to be the alt right?

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[sacsking916 5,000+ posts]

did you check your output of the alt itself? like at the the terminal of the alt and the bracket as the ground?

 

[xxxbasshead 10+ year member]

i checked the output on the wire from the big 3 that goes to the alt. and used the car frame as the ground and got the same results as the batteries. 11.XX

 

[sacsking916 5,000+ posts]

i checked the output on the wire from the big 3 that goes to the alt. and used the car frame as the ground and got the same results as the batteries. 11.XX

battery light or alt light on on your dashboard?

 

[xxxbasshead 10+ year member]

the battery light and emergency brake light on my dash are actually "stuck" on the on position even when the brake is down. took it to a shop and could not find out why so that does not help unfortunately. but the lights obviously turn off when the car does

 

[The_Grimy_One 10+ year member]

I have this same issue. Except I messed mine up. My batt light is on, just got my batt tested, its ok. But what had happened is that my alt power wire got grounded out. Got a new alt, but it still seems to not be charging the batt. I have no idea what it is. Sorry to thread Jack, but my car is currently fukced up to. In your case tho, I feel its the alt. My battery has almost drained, and I have been driving it around, so there is an issue between the alt and the battery, I think //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

 

[xxxbasshead 10+ year member]

sux to hear man. yea i am pretty sure it is the alt. but i will have the battery tested tomorrow to rule it out. hopefully i get a HO alt instead of cheaping out to get a reg output alt!

 

[supermaxx123 10+ year member]

will your car run without the battery?

 

[xxxbasshead 10+ year member]

i dont know, i am working 12 hour shifts today and tomorrow so wont be able to get anything done til sat.

 

[The_Grimy_One 10+ year member]

Mine will not. But I got another alt. I'm guessing the sensor or wire that is between the alt and the battery is bad. Any ideas?

 

[sacsking916 5,000+ posts]

Just remember this, a bad alt kills batteries and vice versa. So having discharged batts can kill your alt. Charge then test batts. Can't get an accurate reading from a dead battery.

 

[xxxbasshead 10+ year member]

Have u checked all the fuses in the fusebox under the hood?

So if the alt is still good the car should run without a batt? Or just turn on?

 

[sacsking916 5,000+ posts]

Mine will not. But I got another alt. I'm guessing the sensor or wire that is between the alt and the battery is bad. Any ideas?

What kind of car? Some cars alts are ran through the pcm.

 

[xxxbasshead 10+ year member]

just remember this, a bad alt kills batteries and vice versa. So having discharged batts can kill your alt. Charge then test batts. Can't get an accurate reading from a dead battery.

but if the resting voltage yesterday was 12.7 and now they are not getting charged would it not be because of the alt? Considering the stereo and all other equipment has been off?

 

[sacsking916 5,000+ posts]

Have u checked all the fuses in the fusebox under the hood?
So if the alt is still good the car should run without a batt? Or just turn on?

Your car can function without a battery once its started. An old way to test if an alt is bad was to disconnect one of the battery terminals but in most new cars this isn't an affective method.