Car Acting Wierd If Don't Drive It For A Few Days

1995 Mustang GT. 165,000 miles. So it started back in August I left the light on, battery died, jumped it, then car died again when using too many electronics (radio, windows opening, I was messing around), then had to jump start it again, then it was fine. This all happened in one day.

A week later I let the car sit for a few days and it started to drive then the battery light flickers and it tries to die but then drives fine after like 20 seconds. The same thing happened in November after letting it sit for 3 days. Then today I didn't drive it for 3 days since sunday. And when turn the key (not all the way to turn the car over but just so electronics turn on) the dashboard lights flicker for a few seconds and then turn on after a few seconds. The radio was also off and was reset almost like when you unplug the battery and it resets the radio. Then it drove fine though. Keep in mind nothing was left on in any of these situations to 'drain' the battery. Since August a belt has been squeeling on start up and then it stops after driving or waiting a minute, its gotten more frequent due to colder weather I'm assuming. It might even be the alternator or a pulley near it it sounds like. Anyways why is the car being weird if it sits for a few days? Maybe the alternator or battery problem from leaving the lights on and draining the battery back in August?

NOTE: Battery was tested @ Discount auto parts in August and it came out fine. Charge was lower than normal but it was still good enough to use the battery. Although AAA's battery meter said the battery was bad. Also the car only does this if I don't drive it for a few days, if I drive it everyday it does not do this at all.

jozsefsz said:

If AAA's battery meter said it was bad, I'd be suspicious of the battery. There are a number of different tests you can run on a battery - AAA may have put a bigger load on it and seen problems. The flickering problems before you start the car would point to a bad battery or cables / grounds.

You could also have an alternator going weak. In my experience about 150k is the usual lifespan of a Ford alternator. It starts with a sporadic battery light, and then gets worse. If it's the original, it's probably time for a new one (too late for brush-pack replacement if it's already showing symptoms - without more rebuilding). Toyman's suggestion for a test will find most problems.

Our cars do like to drain the battery after a while not running. Mine usually won't start if it sits for a couple of weeks, even starting with a full charge on a good battery and with a good alternator. I've checked for power drains and don't really have any one substantial draw, just a whole bunch of small ones.

Most likely both or all 3 (battery, alternator, cables) I'd suspect. Consider the age of the car, I'd replace what isn't relatively new among those 3. Probably easier than troubleshooting & guessing (sucks when a bad alternator kills your new battery or visa versa).

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I actually checked the alternator with a voltmeter in august and it came out fine. Also the battery I tested today with the car off and the car running and the voltage was good as well. I don't know maybe the alternator is going because it looks old so I'm pretty sure it hasn't been replaced during the lifespan of this car.