Andyp

I have a 2008 mustang gt. Just yesterday went out in the morning to go to work and it cranked longer than usual and slowly till it finally started up and ran perfectly fine. I tested the battery so far today and it was fine. On break time while I was at work I tried starting it and same thing except worse (took a little longer) and again fired up ran just fine. Turned it off and figured I'd try it once more before going in and it fired right up no problem. Then before I left it did the same thing as before. Seems when it sits for more than a couple hours it doesn't want to start. The guy that tested the battery said the battery was fine but when we tested it that it didn't charge real fast while running. The graph on the machine showed it climbing slowly where he said it should rise quickly and that maybe my alternator was going bad. I'm not too technically advanced when it comes to cars but I was curious if anyone else had this issue? Because if it was the alternator I didn't think it would affect it starting like that. I'm going to get that tested next regardless just wanted to know if anyone could offer me more foresight with a problem I could be facing. The only other thing I can think of would maybe be the starter but again I'm not well practiced when it comes to car mechanics.

Ford-a-tude

You didn't say how old the battery is. If it's still the original from 08 I'd start by replacing it regardless of any other issues you may find. When the car is slow to crank and the starter sounds labored, it's definitely the battery. It isn't charging properly and can not deliver the cranking amps it was designed to. This could be due to the battery's age, they do wear out from constantly charging and discharging which is normal. If the battery is fairly new and it hasn't been run down too many times, it's most likely the alternator not providing enough charge. In my experience alternators tend to just FAIL rather than slowly go bad. The s197 alternators are also known to have a high failure rate so getting it tested may not be worth the effort. I would proactively replace it to be safe. A mechanic with a smart battery tester should be able to diagnose your battery's charge holding ability. I would avoid your local auto parts store unless it's a place with an actual garage.

Andyp

I know it's been a while but it has a new battery in it now and no exessive drain. The key off amp drain is about 30 milliamps. It now recently went a whole week driving it everyday Monday-Friday until Saturday went out to leave around 1pm and the battery was dead. Charging system was checked at my brothers garage he's the mechanic of the family. We still have had no luck pinpointing the problem and are trying to avoid replacing the alternator when the charging system is checking out ok. I probably will have to take it to a dealer because right now we are both kind of stumped.

Dino Dino Bambino

If you have a digital voltmeter, check the battery voltage with the engine off, and again with the engine idling (no electrical accessories running). Report back with the results.