So about three weeks ago my wife was driving my car (95 civic dx), and she pulled into the parking spot and right before she took the key out of the ignition the car died, and she couldn't restart it.

So I came home from work, and tried starting the car, but it wouldn't start, the batter was dead. So I figured it that the alternator must be dead and the car must've been running of the battery and drained it (btw the battery is bran new, maybe 2 month old). So, I didn't have time to do anything with the car for two days, just let it sit in parking spot. Two days later I came out, pulled my other car next to it, and was gonna try to start it with jumper cables. But before I even connected jumper cables, I decided to try starting it again. I turned the key in the ignition, and it cranked weakly, but to my surprise it started, on the first crank! So I'm like wtf - I let it run for a few minutes, shut it of, restarted, it started fine, the battery was recharged, the lights working. Ever since it's been running normally, battery is charged, starts fine, battery light doesnt go on.

So on Saturday I took it to the shop for an oil change, and I had the technicians test the battery and alternator, and both passed the test. I described to them what happened, and they couldn't tell me what might have happened.

To make matters worse, in the two days that the car was dead, I was so sure that it was the alternator, that I went ahead and ordered a 135amp alternator of ebay. So now I face a dillema - do I replace the alternator anyway? I also need to upgrade the cables from alternator to battery, because stock wires aren't suitable for 135amp.

On the other hand, I could probably return the alternator, but I'm afraid if I do, the old one is gonna go soon - after all it has 145k miles on it.

So what do you guys think might have caused it? I remember on my old GS300 I had a dying alternator, but at least the car showed the symptoms. It would die, then I could jump start it, but after a while the battery light would go on and it would die again. But in this case - nothing, been driving for three weeks and not a single symptom.