Alternator putting out 11.6 volts...

[Wahoo]

So I've had a history of low voltage on the scan master and battery not fully charging. I had my alternator tested by advance auto before, and they said it was good. Now I've been busy doing body work because I'm going to be painting the car, but today since I wanted to start it, I decided to check voltage at the bolt/nut on the back of the alternator, and the other lead to the negative terminal on the battery, and it showed 11.6 volts.

This is with the engine cold start, so it was idling high, also the chip was reset because I had the orange wire disconnected, but its a stock car anyways.

Isn't 11.6 volts low coming from the back stud/nut on the alternator, at a high cold idle? Battery wasn't fully charged either, so it should of needed to be charged by the alternator.


Thanks!

 

[turbonut85]

Too low. Check for connection issues and then have the battery tested. The alternator should be putting out more voltage than that at cold idle for sure.

 

[GNRick]

Remove the alternator and have them check it. The hand held tester that they use is not reliable.

 

[Wahoo]

Remove the alternator and have them check it. The hand held tester that they use is not reliable.

It was removed when checked,they put it in there test stand and through a belt on it and tested it.

 

[GNONYX]

Maybe the alternator needs to be rebuilt
http://www.ebay.com/itm/CS144-Delco...rly-/190670436560?hash=item2c64d7f8d0&vxp=mtr
http://www.ebay.com/itm/CS144-Delco...rly-/200735758383?hash=item2ebcc8982f&vxp=mtr
Check and see if the an original GN 120amp, and not the cheap replacement 105amp
When my alternator gave out, it was replaced with an over the counter 105amp; it was good until it started to only give 11.0amp to 12.5amp
I found the original 120 amp alternator, rebuilt it with the above parts and now pushing 13.5 to 14.0amp at start up
Just a though

 

[Chuck Leeper]

Could be that the exciter circuit is dead. Does the dash lite come on at key on?
You could have a no excite condition, and are reading batt volts during your test.

 

[Wahoo]

Could be that the exciter circuit is dead. Does the dash lite come on at key on?
You could have a no excite condition, and are reading batt volts during your test.

Thanks I'll check that when I get home from work. I did install New gauge cluster bulbs in the dash so the battery bulb is New.

 

[Wahoo]

Could be that the exciter circuit is dead. Does the dash lite come on at key on?
You could have a no excite condition, and are reading batt volts during your test.

By dash light do you mean battery light?

With key in on position but car not started the battery light comes on. It seemed to also stay on when the car is started, I only let it idle for 30seconds or less and checked what my scanmaster had for voltage which it showed 10.9/11.0 volts

The car isn't driven currently it's just sitting in the garage.

 

[Wahoo]

Bump

 

[Mark E.]

Check for voltage at the brown wire at alternator. no 12v there, no output. Key on of course.

 

[v6turbo87]

If the light stays on with the car running the alternator is not charging. Check that the connector at the back of it and make sure it isn't damaged. Take it somewhere else to be tested.

 

[Wahoo]

Check for voltage at the brown wire at alternator. no 12v there, no output. Key on of course.

Are you talking about the stud on the back? With car not running? Just key on?

 

[Chuck Leeper]

Are you talking about the stud on the back? With car not running? Just key on?

The small wire w/ the plastic plug on it........

 

[Wahoo]

The small wire w/ the plastic plug on it........

My car is a hot air, I don't k ow if that makes a difference.

Here's a picture, the red wire in my hand was connected to the stud, this is an old picture after I had the alt out for awhile I didn't know where it went.

 

[Reggie West]

I rebuild those so they put out a solid 200 amps. You will see 14.5 volts at 1000 rpms.
Cost is $230 plus shipping.

Let me know if you are interested.

 

[Wahoo]

I rebuild those so they put out a solid 200 amps. You will see 14.5 volts at 1000 rpms.
Cost is $230 plus shipping.

Let me know if you are interested.

Thanks for the offer, I don't know if it's bad just yet

 

[Wahoo]

Check for voltage at the brown wire at alternator. no 12v there, no output. Key on of course.

no Brown wire

The small wire w/ the plastic plug on it........

Where in this picture, the red and white wires? Measure with leads one on each wire?

 

[Chuck Leeper]

From the looks of the batt feed wire, it's seen it's better days...Looks like it "used to be" red.
I'd be for replacing it.

 

[Wahoo]

From the looks of the batt feed wire, it's seen it's better days...Looks like it "used to be" red.
I'd be for replacing it.

I haven't tried cleaning it, the engine compartment has been dirty since I owned the car(not long and is being stripped for painting)

But shouldn't the alternator be putting out more voltage?

Do they make a replacement cable for the battery to alternator, I'm not opposed of replacing it if it's a problem.

 

[Mark E.]

Check for voltage at the brown wire at alternator. no 12v there, no output. Key on of course.

Ooops. This is for 86 87 setup.