Battery / Alternator / What Else?

[PitBoss1]

I have an '06 Corolla, with about 60k miles on it, nearly all highway. I work nights, and commute 100 miles round-trip. I have an after market radio in the car, a pioneer, which I use to listen to my iPod. I am in the habit of leaving the iPod plugged in, and in the glove box all the time. I have had this setup for about 8 months now. I am mentioning the iPod setup as it is the only thing that is not 'stock' in the car. I am fairly certain that it is not at fault for my problem.

I left for work in the early evening, and the temperature was about 55 degrees or so, with light rain. I noticed no problems at all as I pulled into my parking spot at work.

When I went to my car after work at 02:30 am (35 degrees) I noticed that the keyless entry didn't work. I had to manually unlock the door. Turning the key yielded the usual dashboard lights and the bells that indicated that my seatbelt was not yet fastened. Then when I tried to start it nothing happened at all. No solenoid click - nothing. I got a jump from the security folks at work, and it started right up.

I made the 50 mile drive home, and noticed that if I applied the brakes, the headlights would dim. When a turn signal was blinking, there was a slight dimming of the headlights in time with the signal. At one point, I turned the headlights to 'bright', and everything died immediately. I quickly turned them back to low as I coasted along, and it all came back up just fine.

After I pulled into my spot at home, I turned the car off. As an experiemnt, I tried to start it, and it behaved exactly as it did when I first got into it after work - nothing would start.

My question is this: Is it just the battery, or could the alternator be at fault as well? Or something more sinister?

One odd thing - none of the usual idiot lights came on to indicate any problems. No battery light, no alternator light, nor a 'check engine light' - nothing.

[JasonA]

Seems like the battery. The alternator is supplying enough to keep the car running, but the battery's not there to start it. I would have the car jumped and make a trip to Advance Auto or AutoZone, where they can test your battery and your alternator.

[Rdkill]

Well the the problem is that if the lights are dimming when you activate brights, it very well could be both battery and alternator. If you have a bad battery, even really bad, the alternator should still put out enough power to run everything while the engine is on. Your battery is definatly shot(unless its relativly new), but I would say it could be the alternator as well. Make sure you have BOTH checked. If you replace the battery and keep a bad alternator it will kill it rather quickly as the battery will not be getting a full charge. If you take your battery voltage at the terminals with the engine running, it should be 14.4 for a perfect alternator. We had a bad alternator put out just 13.8 and when tested it was putting out 50% rated power....

[PitBoss1]

Replaced the battery, and it seems to be OK for now.

[JasonA]

I would have the alternator checked as well. There may have been a reason the first battery died.

[PitBoss1]

I did get the alternator checked, at Autozone of all places. Yea, I know - they aren't really professional mechanics there, but the guy seemed to know how to read the machine that he clamped onto my battery cables - my apologies to dedicated Autozone employees all over the world, but the dude was reticent to attach the machine in the first place. His initial diagnosis of my problem was that I had a short, and I had to talk him into hooking up the device. I got the distinct impression that he may have been stoned - or constipated, I couldn't really tell. Understand - he was already outside, finishing the same procedure with another customer. At any rate, the alternator's good-to-go.

[JasonA]

I used to work at Advance...I know how it is with most of those guys. Either way, it's pretty hard to mis-read the machine, so if the machine said your alternator is fine, it most likely is.