Ok. Got in the car, drove to work this morning. Everything seemed normal. Got out of the car, hit the lock button on my remote, and no horn beep or lights flashed. Walked back to car and listened closely- I could hear the doors locking and unlocking when I hit the buttons, but no lights or horn. Thought "Hmmm, weird. Maybe the buttons got mashed in my pocket and turned it to silent lock mode" (or whatever you'd call it). Went inside. Ate lunch at my desk. Left work 9 hours later. Walking up to my car, hit the unlock button. Again, no flashing lights, but then found the door didn't unlock. Even the key-less button on the door handle didn't recognize the proximity key. Had to open the door with the physical key, Ignition didn't recognize the proximity key either, so I had to put the physical key in to turn the ignition. Then nothing. No attempt to even turn over. Dash lights started to dim, so I turned the car off and removed the key.

Called someone to give me a jump, and it fired up, ran, got home, no problem. My Scangauge 2 showed only 12.6 volts at idle, and 13.2 - 13.4 volts once above 1200 rpm. Got home, turn the car off, and it fired back up again without problem. Car off, the battery was reading 12.7 volts.

The battery is less than 12 months old (bought last October, mfr date of Sept.). Stopped at an AutoZone and charging system and battery both tested OK.

I'm positive nothing was left on in the car when I went into work. What could have caused such a significant parasitic drain on the battery to leave it nearly dead after 9 hours?

I also realize that the engine-on voltage is not where it should ideally be, but it tested OK. I'd love to get in there and take some connections apart and clean them as a precaution, but with how god-awful hot it has been here lately, I just can't imagine doing it right now.

Any ideas on what may have led to this behavior? I've got the trickle charger connected now, hoping I won't need another jump after work tomorrow.

 

The factory headunits have been known to draw power when their circuits start failing, as does the bose amplifier.

Search for those topics in here, I believe there's a post that'll let you know what the amount of power being drained from the battery should be when the car's off that's normal, and where it is when a part of the radio is failing.

Edit:
Here you go:

https://g35driver.com/forums/audio-v...cceptable.html

https://g35driver.com/forums/audio-v...-now-what.html

 

Thanks for the reply. I'll look into this if I see the issue recur.

I hooked up the charger last night, but it's only a 1.5A charger, so it was still not topped off by morning. I also found each cell was a little low on electrolyte. 4 were maybe just below the "wink" level, and 2 were a bit lower. Probably added about an ounce of distilled water to the 4 cells and two ounces to the 2 lowest cells. I've seen batteries with lower fluid levels that were behaving fine, so I'm not expecting that to be the issue, but it could have contributed.

Car fired right up this morning, and the system was seeing 13.8 - 13.9 volts while cruising to work at around 3000 rpm. Saw it up to 14.1 -14.2 a few times while accelerating. This is much better than I was seeing last night on my way home.

I'll check on it at lunch, and I'll keep it on the charger at night til I see it successfully topped off. It's also been suggested to me to pull the connections on the Alternator and clean them up.

Hopefully this was a fluke....

 

Turn over was nice and quick when I went to lunch just now. I remember how slow it sounded before I got a new battery, though it never struck me as slow until I had a new battery installed. Keeping fingers crossed that it was a weird fluke and/or related to slightly low levels of electrolyte combined with the ludicrously hot weather this past week.

 

Get the amount of drain with the car off checked, that should alleviate a lot of the uncertainty.