Been a while since I've posted here (read: broke college student, reading the forums only wants to make me spend my little funds on more mods)... however, this issue that has come up begs the advice of MF

Battery started dying last week on the way to the bar, radio went out, looked at the voltage meter and realized it was dropping quick. Made a quick U-turn and headed back towards my place, on the way back, full death - headlights/tach/speedo. It had been about a year and a half, so cleaned the corrosion off and bought a new battery, swapped it in. Was thankful it wasn't the alternator and dodged an expensive bill.

Flash forward 2 weeks, I drop two buddies off and I'm headed back towards my place. Notice movement on my gauges, I kill the radio and since my headlights are still on, I watch my battery drain to nothing while I just manage to coast into a parking spot at my complex.

Alternator? That's my first idea, but I can't understand why it worked for two weeks of night driving ( headlights/radio on /w no issues). Also, when I go out to my car in the morning, it has enough battery to start magically again, and doesn't drain quickly unless I turn accessories on.

Just kind of stumped, I figure it has to be an alternator issue at this point. If there's anything else I should consider, other than cleaning off corrosion, I'm open to ideas. Just trying to avoid a stiff bill.

Any threads y'all could link to (been googling all day and night trying to find similar issues, and short of turning off accessories and buying a charger I found nothing seemingly relevant) would be highly appreciated.

Sorry for the long post, just want to throw it out there before I drop what little cash I have to spare.

Cheers and thanks y'all!

 

I think you posted this in the 5.0 section...

Nonetheless, have your alternator load tested as well as the battery (despite being new). The alternator is a weak link in an already-iffy charging system. I've read numerous threads where the alternator was not dead but the charging rate was degraded which will slowly discharge a good battery.

 

I right there with you. My 2007 V6 did the same thing only the time difference was a bit longer. I had mine start to go dead while driving and since it was the original battery, I managed to get the car parked and a buddy picked me up and took me to get a new battery. Flash forward about a month and the same exact thing happened again; radio dash lights blinkers,etc. Made it to a parking lot near where I bought the battery. Wife came and got me, took me to the auto parts store and they said the battery was good but was drained. Bought a new battery to get the car home and made it, all the while thinking I had a bad alternator. Car is under warranty so I get it to the dealer who checks it out and says nothing is wrong. Knowing they don't have a clue, I purchase one of those voltage meters you plug into the cigar/12V accessory port in the dash and I watched the alternator voltages go all over the place but never over 13.1 volts. I watched as the battery drained at stop lights to below 12V. Went back to the dealer and complained that the alternator was bad and I had proof (shot video with my phone) and sure enough the alternator was bad (Duh!) Anyway there isn't a way to fix those, you just have to buy new at least for mine its that way. I have the extended warranty and it only cost me $100. New alternator for my car, $260 + tax but I get about 25% off that price because a buddy of mine works at that dealer's parts counter.

Good alternator should be between 13.8 and 14.4 or so on the charge side at idle with no accessories and with everything in the car running, should be stable and fluctuate very little.

 

I appreciate it y'all. Sorry about the wrong section, subconscious clearly telling me to get a 5.0

 

Probably. My experience is, when you have a dead battery, it's making the alternator charge it 100% of the time and that plays havoc with the diodes. If I remember correctly, it used to be that you could replace the diodes, but these days it seems you can't.

I'm not a mechanic, I just played one when I couldn't afford the services of the real deal.