Saturday night at about 4AM I started to head back from Rochester to Buffalo. Just before getting on the highway, my battery and brake light come on.

I'm ****ed, because I though I had a belt problem and figured I'd have to put the stock belt on (which I keep in the trunk). Well, get out of the car, check under the hood and everything is just fine.

I don't know anyone in Rochester that I could get help from at that hour...and I only have the 5mile AAA crap (I need to upgrade) so I decided to get on the highway and drive as far towards Buffalo as I could and then call AAA when it dies.

Turned all the accessories off that I could and set the CC for 90, figuring that faster would get me closer, and the higher engine speed may help produce extra power from the alternator. Turned out that I got home just fine. Phew.

Next afternoon I went out to the car and started it...no battery light. I went out for a drive, and after about 5 minutes the light started to fade on, and eventually stayed on. I've done this about 3 times now...and the light always starts 'off' for a few minutes, but then comes on after a few minutes of driving.

How long can the car keep this up? I'm going to try to get a replacement today, but in the mean time I'm going to just keep driving the car.

Any idea on the cause? This alternator is like less than 1000 miles old.

 

did you get that alt from nissan?

most ppl have been having problems with the ones from pep-boy, autozone and other auto parts stores.

 

No, its from an auto parts store...but I figured an alternator is an alternator.

I'm going to try another one I guess...because its covered under warrenty, but if that one doesn't hold I'll go for a Nissan one I guess.

 

after hearing all the problems i went to nissan and got the new up-graded 125amp alt. the sad part was that i paid $303

 

I got my alternator from Advance Auto Parts and I haven't had any problems with it. It was 160 bucks I think. That was about 6 months ago.

 

Alright guys, more information....

Go out to the car at lunch time. Measure the battery with the car off and its got 12.5V of charge. No problem there, the battery is obviously taking and holding a charge.

Start the car, no battery light yet. Measure across the battery again and see like 14.1XV. Just a hair over 14V. Seems fine.

After a few minutes the battery light comes on, and I measure again...13.5XV...somewhere in the mid to high 13's.

I go out and get lunch, with the battery light on the entire time. When I get back I open the hood again and check...13.1V or so. Still, that should be enough, no?

When does the battery light come on? How much volteage _should_ the battery be seeing when the car is running?

 

I believe the entire electrical system should see around 13.5-14.5V ALL THE TIME while the alternator is operating. If it's below 13.5, I'm pretty sure there's a charging system problem. You know for sure if the battery light is on--battery light indicates there's a discrepancy between the voltage received at the battery, and the voltage coming out of the alternator.
Also, don't overlook the idea that it could be a bad harness or ground somewhere... or mis-connected harness.

Also FYI, my experience with batteries has usually been that brand-new or just-fully-charged batteries tend to put out 13.5V (w/o engine running)... though these were all maintenance-free batteries. My 2k's OEM battery (low-maintenance, i.e. liquid electrolyte) sits at 12.5V consistently with the engine off, although it's also 3 years old.

 

check that harness that has two plugs that go into the alt. i had a battery light and brake and this was my problem...

 

What was wrong with the harness? Did you replace it? Was it not pluged in?

Are you talking about the clip-in plug, or the bolt on big-**** wire?

 

clip plug in has 2 wires, mash those in there, that is what i had to do. the wires came out hte harness so i took a long allen key and shoved it deap in there and i have not had any probs.

check both connections

 

Replaced the alternator yesterday.

Both of the connections were fine. However, I have a slight oil leak from my left (front) valve cover. It appeared that that oil was finding its way to the alternator. I suppose that could short it out. There wasn't much on there.

 

Oil wouldn't short it out, but it could interfere with the brushes that touch the alternator rotor (insulating the brushes so they won't conduct)... that would cause your intermittent issue.