My beater coupe wouldn’t start and the battery wouldn’t hold it’s charge after sitting for the last year. I bought a new battery and it started fine. After sitting for a few days, it was totally dead and needed a boost.
Once the car is boosted and driving it sometimes loses all power and dies. This leads me to believe it’s the alternator.
Now here’s where it gets weird. Yesterday it started after not being touched for a week. It idled fine until my bro’s gf stalled it… then there was no juice to start it again. We left it for a few hours, then came back to it and somehow there was battery power again.
Alright, that didn’t last long. It was fine all day (lots of stop and go and I turned it on/off many times)… now it just shut off while idling, so I boosted it and drove home. It wanted to die the whole way unless I kept the revs up. When I pulled into the driveway, it died.
Hey man, it sounds like the alternator, when you drive it, it slowly runs out of juice, then when you let it sit for a while, the battery regains some of its charge. Also, when you rev it up it seems to run better? That sounds like a bad alt.
You can bring the alternator to crappy tire and they will test it for you for free.