YACT: Woe is me... Any way to test for failure of alternator?

[weirdichi]

Just got home and the battery light kept flickering (I had no other electrical draining devices on, such as radio, a/c) and finally went away. It did NOT die, but it went away. Car still had power like normal. I checked the voltage and it was 14.2. After the engine cooled for a bit, I checked the voltage again and it's about 13.5. What is wrong with this damn car???

 

[Pacfanweb]

I've got 100 bucks that says I can go to any car lot, start every car, remove every negative cable with the engine running, and not one single one will be damaged.
I realize that repair manuals say not to do it, but the fact of the matter is, 99.99% of the time it won't hurt a thing.

Example: My 99 Tahoe. I start it one morning, drive 30+ miles. Stop to get something to eat. Get back in car, no battery power at all.
Great, I say, dead battery. Get out my jumper and open the hood. Keep in mind this is a GM with side post terminals.

To my surprise, I find that it's not a dead battery, but the actual Positive terminal, the part with the threads that the cable screws into, has come loose, and the whole trip has been sitting there moving around, making contact, and breaking contact. I could push it back into the battery and the truck would start. Drove it back 25 miles to the dealership(it was under warranty), again, with no damage.
No harm done. New battery, ran like a champ. Still does.
If you don't know what you're doing, maybe you should leave it do the professionals, but like I said earlier, removing the NEGATIVE cable will not hurt a thing. I've done it hundreds, if not thousands of times on brand new cars with no ill effects at all.

 

[Pacfanweb]

Originally posted by: weirdichi
Just got home and the battery light kept flickering (I had no other electrical draining devices on, such as radio, a/c) and finally went away. It did NOT die, but it went away. Car still had power like normal. I checked the voltage and it was 14.2. After the engine cooled for a bit, I checked the voltage again and it's about 13.5. What is wrong with this damn car???

14.2 should be the max voltage output. If your voltage regulator is crapping out, it can vary the voltage and cause the light to flicker. Most regulators are built into the alternator these days, so if your battery is testing okay, it may be alternator time.

 

[raanemaan]

Take the car to an autozone or other parts houses they will check the alternator and alternator for free. The alternator is most likely going bad. The brushes could be worn or a loose connection inside the alternator. If you can get to the back of the alternator you can put a scredriver against the back bearing. The scredriver will be pulled against the alternator because of the magnetic field created. Just be sure you don't short anything out. I too have pulled the battery cable off to test the alternator but would not recommend it on a newer car. Too many sensitive electronics in todays cars for me to take a chance on it.

 

[weirdichi]

Autozone tested the battery and alternator and everything was fine. Must be connections. I'll clean and update tomorrow.

 

[MikeMike]

i hadmy alt crap out on me once, it wasnt fun.

driving home, i was bout a min away from my house, all of sudden everything becomes dim, my bass gets quieter. i look at the volt meter, and it reads 12 volts.

get home, tell my dad, and then we dont worry.

try to start up the car the next day, the alt had drained the battery.

so we try to jump it. it wont take a charge.

in the end...
The alt was gone, and the battery had lost one cell causing it to not take a charge, and only give out a possible 10 volts iirc.

MIKE