I purchased a new car battery the beginning of September and 4 weeks later it was leaving me stranded at random times and needed to get it jump started. Then I'd drive it on the interstate for a little while to charge up the battery and it would be okay for a few days. Then I got to leave the grocery store one day and when I turn the key click, dead again! It got to the point where the car would not start without a jump. I thought it was a defective battery. Under warranty O'Reilly reluctantly swapped it out for me after complaining about it leaving me stranded all the time. I thought I had a parasitic drain that was draining my battery while it was hooked up. I got the new battery from O'Reilly's 3 weeks ago and I was disconnecting it every time I shut the car off so the parasitic drain wouldn't drain the new battery. But yesterday I stopped at a gas station and when I went to turn the car on click,dead again! Unlike before where I'd drive on the interstate to charge up the battery and it would last a few days as now as soon as I turn the car off that's it, dead as a door nail. But how? I was disconnecting the new battery everytime I shut the car off. Which leads me to believe the problem was not a parasitic drain but a bad alternator. That before was dying and was able to charge up the previous 4 week old battery somewhat that it would last a few days. It did this about 5 times before it finally would not charge it at all. Then I got the new battery that lasted 3 weeks. I believe once whatever juice the battery came with was depleted from starting the car the now completely bad alternator isn't charging it one bit.
This happened even though O'Reilly's scanner kept saying everything was good with the battery, alternator and starter.
Even before they used the scanner the first time after I arrived at O'Reilly's they had to use a jump starter to get the car started and then they ran their scan tool and everything still kept coming up as it was good with the battery, alternator and starter.
So before I run out and buy an alternator has anyone experienced something similar that turned out not to be the alternator?
​​​​​​Looking forward to hearing from you all.

 

Since you have been disconnecting the battery, it suggests that the car is no longer charging the battery and all starts have been done completely on a charged battery. Remove the alt, have the parts store bench test it. See what that yields. Also, check all connections from alt, starter and battery for signs of corrosion, if there are, clean them off as that can cause weird issues. I actually had a parasitic drain on my 2004 Monte, but it was only an issue if I didn't drive the car for about 3-4 days.

 

Thanks Maniac, I'll be able to do it this weekend. I'll post what they say.

 

Alright, so today I did a voltage test on the battery, and it was registering 12.5 volts with the car off. All terminals are good with no corrosion and with the car running it was mainly staying around 14.5 volts but would bounce between 12.5, 13.5 and even registered as low as 9.6 volts a few times. Jumped it again and drove it to AutoZone where I took the alternator off the car and inside for a bench test. Not knowing what brand of alternator it is they ran the test as a Delco then as a Bosch and passed both times. When I got home I checked the voltage on the battery with the car running and it was steady but lower at 14.0 volts with it dipping to 13.2 at times and didn't matter if the lights were on or off. So with the bench test done I have to accept that both test's that were done at Oreily's were accurate. As far as the starter, and alternator being good. But now that I've seen that the alternator is neither a Bosch or Delco I feel that the alternator that is on the car is not the correct one. I thought for sure it was the alternator so know it's on to my mechanic to figure out what the heck is up with the car not keeping the battery charged.

 

I find it weird they needed to know if it was a bosch or delco alt. I have never had that be a requirement for bench testing the alt. For the record, I have had an alt that failed and passed a bench test at a bunch of different stores on different brand bench testers. I finally declared it failed when it was the source of a burning electrical smell. Once I replaced it, my journey to find the source of my parasitic drain ended (despite positive bench testing, it was the alt). But how to diagnose that is the failure, I am not sure, especially since you said you have disconnected the battery and still had it go dead. I also know a volt meter can read the battery has 12v and the battery still have problems (I just had a lawn tractor battery that was putting out 12v with my volt meter but not enough amps to operate the starter on the tractor, that was found by borrowing a battery and re-testing).
As for the right or wrong alt, many vendors make them for these cars. If there is apart number on your alt you can cross reference it and double check.

An old-school battery test (that I would NOT recommend on these cars) was to start the car, while it was running, disconnect the battery. If the car continued to run without issue, the alt was good. If it failed, the alt was bad. The reason I would not do that with these cars, too many computer devices that may have issues with doing that.

Does the car have any aftermarket items? Stereo equipment, remote starter, anything non-factory?

 

I think I'm going to do what what you did and just pick up a new alternator. The car does have a couple of things that are aftermarket. The stereo which I have since removed since it wasn't working only to find out the stereo/Cig fuse for the stereo had been removed. Probably was draining the battery because after I put the fuse the cigarette plug had current car and could charge my phone with the car off. I actually want to pick up a factory radio from a junkyard since I've read it's actually used to clear the change oil reminder and other reminders. The other is it has HID headlights that I don't think are wired correctly to the light switch. For instance with the light switch pushed in the headlights come on. Pulled out half way the headlights go off. Pulled out all the way and the headlights come on. After turning the car off pushing the light switch all the way in turns off all the car lights. So new high output alternator and led marker lights I think should take care of that. Also going to bypass the anti theft device using the 20 ohm resistor. I already have it just need to install it.

 

So, when talking about electrical gremlins and various drains.... Hearing you describe incorrect operation of the headlights, I would recommend chasing that down to understand "why" they don't work right. For all you know there is some weird wiring causing some goofy problems from shorts to drains.

 

I think you're right. The fact that with the car running and the switch in the off position the headlights come on and with the car off and the switch in the off position turns them off maybe the headlights are still drawing current.
I was recommended an auto electrical shop today that I will be taking the car to if I am not able to rewire them correctly.

 

Okay I'm back with some great news. So the two test from O'Reilly's showing that the battery, alternator and starter were correct. The two bench test on the alternator showing that it was good was also correct. After I replaced the second battery in two months I noticed that the rubber from the negative cable protector was being sandwiched between the battery terminal and the washer type battery connector from the cable. Even though the screw was there to make contact with both I kept wondering that the connection to the battery wasn't so solid because of the rubber. I had already removed the red rubber protector from the positive cable because it was all scraped and chewed up somehow. As someone pointed out how bad it looked in another thread I started Lol. Sure enough as soon as I removed the black negative rubber protector and screwed the terminal right up against the battery the car has started every time with no issues. Looks like the rubber between the battery and the cable was keeping it from making a solid connection to the battery and that's why the battery wasn't able to charge when the car was running. The black crud looking stuff on the white sticker on the battery is from coolant that fell on the battery while adding it to the radiator. I'm going to put on a good amount of some thick battery terminal grease to keep the terminals protected. Very happy now that I don't have to worry if the car is going to leave me stranded at the grocery store or if the car is going to start in the morning so I can get to work. Thanks for your input Maniac

 

I think I mentioned how bad those things looked. I did the same thing you did, took them off and put grease around the terminals. Just remember, grease AFTER the cables are tightened down.