I recently bought my e28 with a cheap USA Industries alternator already installed, which would not charge my battery. My battery light was working properly, and I also tried a new voltage regulator and ground strap that didn't change things.
So, the next step was to remove the alt and bring it to Advance Auto for testing. The first store I stopped at had trouble since the alternator didn't use one of their wires on the machine (some little white connector). They got the test started eventually, and it stopped at "charge circuit not working" and wouldn't go further. They couldn't tell me whether this was a problem with their machine or whether it was a problem with my alternator.
The second store spent 20 minutes trying and failing to get the alt hooked up for the test, and just gave up.
Thankfully, a third store had a replacement alternator in stock so I just went with that. I lucked out in that it was $85 plus another 30% off with an online coupon, so $61 total!
Now I have almost 14 volts in my system again.
Advance Auto Alternator Testing Fun!
Re: Advance Auto Alternator Testing Fun!
I've had things pass that test that didn't work before so I wouldn't call it definitive. The alternator I put on my truck had some odd regulation problem that let the voltage swing about 2 volts in a regular pulse. Their tester said everything was fine. Trying to drive it at night, it was obvious things weren't fine. I got them to replace the alternator anyway, the replacement worked perfectly.
Re: Advance Auto Alternator Testing Fun!
Yeah I have read stories about how the tests are pretty worthless sometimes. For me it was the very last step before replacing the alternator entirely, since I was pretty sure I had checked everything that was cheaper.gadget73 wrote:I've had things pass that test that didn't work before so I wouldn't call it definitive.
It made me a bit sad though, since the crappy broken alternator looked almost brand new.
Re: Advance Auto Alternator Testing Fun!
Happens. I have had it confirm things for me though. I had low voltage output on my Towncar, the tester came up with a dead rectifier, which made sense. That was the second alternator. The first one lasted about 2 weeks before it died. At the time my smart hand was in a cast after I tried removing a pinky with the clutch fan, so I ended up changing it with basically an elbow and my stupid hand. It took considerably longer than it should have, luckily the alternator on that car is right up top.
Re: Advance Auto Alternator Testing Fun!
My 140A alternator I rebuilt tested perfect at an O'Rielly's three different times. But it never put out more than ~12.3v when in the car.
Re: Advance Auto Alternator Testing Fun!
I would replace with a Bosch 90 amp from a junker before I bought a new Chinese alternator. Other than brushes/regulator, no troubles.
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Dave_in_VA
- Posts: 425
- Joined: Feb 12, 2006
- Location: Baltimore, MD
Re: Advance Auto Alternator Testing Fun!
As someone who works at Advance Auto and has tested numerous alternators I can say that you are at the mercy of the person doing the test. If the alternator tests good but the customer insists that its bad I have to do a "read" of the customer. Are they trying to get their money back or are they just wanting a replacement alternator? Many times, I have people who bought an alternator thinking that it is the problem when it turns not to be the case. Then they try to return it claiming it is defective but don't need another one since they "got one somewhere else".
I have also people that don't understand that there is more to the system than just the battery and the alternator. I try to explain to them about grounds and cable condition and such and get a blank stare.
I am not a huge fan of the tester because of a lack to training provided to the employees other than how to set it up and if it says its "Pass" it's good and if it says "Fail" it's bad.
Also remember these machines are primarily for determining if an alternator is bad for warranty replacement. You have to look up the alternator to get the test code and the code does vary depending if the alternator being tested is a new or remanufactured. What the difference is I don’t know. I always go with the reman code when I don’t know what the customers unit is.
Sometimes you can get a false fail if your ground is bad. Clipping onto a crusty corroded case isn’t the best way to ground.
I have also people that don't understand that there is more to the system than just the battery and the alternator. I try to explain to them about grounds and cable condition and such and get a blank stare.
I am not a huge fan of the tester because of a lack to training provided to the employees other than how to set it up and if it says its "Pass" it's good and if it says "Fail" it's bad.
Also remember these machines are primarily for determining if an alternator is bad for warranty replacement. You have to look up the alternator to get the test code and the code does vary depending if the alternator being tested is a new or remanufactured. What the difference is I don’t know. I always go with the reman code when I don’t know what the customers unit is.
Sometimes you can get a false fail if your ground is bad. Clipping onto a crusty corroded case isn’t the best way to ground.
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Nebraska_e28
- Beamter
- Posts: 9136
- Joined: Apr 13, 2006
- Location: Council Bluffs, IA
- Contact:
Re: Advance Auto Alternator Testing Fun!
/\/\/\/\ What Dave said. As someone that works at one of Dave's competitors I too have seen what he mentioned. The machine is simply pass/fail, but most operators dont take time to print/interpret the results. An alternator/starter that is borderline bad may pass. Another factor in this is heat. 1 cold test of a unit isn't always sufficient IMHO.
In your circumstance, what was the idle voltage of the alt while on the car? If for whatever reason there is faulty connection or excessive resistance in the igniter circuit of your alt, then it will never charge. 1 exception to this is if the car is revved above apx 3k rpm. This will activate the alt to start charging despite it sensing signal thru the ign circuit, aka blue wire.
In your circumstance, what was the idle voltage of the alt while on the car? If for whatever reason there is faulty connection or excessive resistance in the igniter circuit of your alt, then it will never charge. 1 exception to this is if the car is revved above apx 3k rpm. This will activate the alt to start charging despite it sensing signal thru the ign circuit, aka blue wire.
Re: Advance Auto Alternator Testing Fun!
Idle voltage was 12.4-ish. I have since replaced the alternator and have normal voltage again, but before I did that I replaced the VR (no change) and also confirmed that the exciter circuit was intact. Then I tried jumping voltage to the exciter circuit manually, to no avail. Then I replaced the ground strap, which was pretty sad looking, and had no change.Nebraska_e28 wrote:In your circumstance, what was the idle voltage of the alt while on the car? If for whatever reason there is faulty connection or excessive resistance in the igniter circuit of your alt, then it will never charge. 1 exception to this is if the car is revved above apx 3k rpm. This will activate the alt to start charging despite it sensing signal thru the ign circuit, aka blue wire.
Re: Advance Auto Alternator Testing Fun!
did it charge at all, or zip? The one I had with a bad rectifier charged a little but in the 12.x range. It would pick up less than 1/4 volt from not running.
Re: Advance Auto Alternator Testing Fun!
The battery constantly ran down, so I guess it didn't. Is that enough to tell if it was charging a little or not?gadget73 wrote:did it charge at all, or zip? The one I had with a bad rectifier charged a little but in the 12.x range. It would pick up less than 1/4 volt from not running.