[JeromeS13]

So, I got an email from OnStar last night (after I went to sleep) saying that my battery was critically low in my car... I got up early and went out to leave for my track event today @ 5am (about 1.5 hour drive). I go to pop the trunk. Nothing. After I crawl through the pass-through and get access to the battery, it's only putting out 1 volt! Great! Fortunately, there's a Walmart just down the street, and they had a 6H/Group 48 in stock. I got it all swapped out (because I definitely wasn't going to miss my track event).

Track event was a success (videos to come).

After leaving the track event, I see the voltage gauge indicating lower than normal (usually right around 14 or a little above). So I connect my OBDII dongle and get a reading. It's only putting out 12.5 volts with the car running! This is with a BRAND NEW battery... So, I pull over and make sure my alternator belt was still on, which it was. I restart the car and it puts out 13.6 - 14.0 volts for the first 20 seconds or so, then slowly lowers and levels out around 12.5 volts... Ugghhh.

I had my OEM battery charging while I was gone, and I'm cycling through charging it with a 15 amp automatic charger. I'm not sure if it's going to come back to life or not..

Looks like I'll be making an appointment to have them check out the battery/charging system, and might as well have them check my transmission fluid leak while they're at it...

[camaro5]

Alternator is done.

[JeromeS13]

Follow up:

After driving the car a few times, it looks like the alternator charges just fine sometimes (~14.0 volts), and other times it sits around 12.5 volts while running. According to the dealership, this is normal.

I think I may have left my Power Magic Pro on (for my dashcam), while it was in the garage for 4-5 days straight... I believe that may have been the source of my dead battery...

[SSDan]

Good to hear that all is working now. I've read other posts about charging voltage and the consensus is that the voltage fluctuates like yours is doing. Apparently the on board computers monitor load/demand and then cycle in and out of charging mode as needed. Thus the readings will bounce between 12.5 and 14 volts.

[ChevyRules]

Yep normal. It improves fuel economy by doing this vs the old behavior of the alternator always pumping out 14 volts.

[camaro5]

Originally Posted by JeromeS13

Follow up:


I think I may have left my Power Magic Pro on (for my dashcam), while it was in the garage for 4-5 days straight... I believe that may have been the source of my dead battery...

At least that is easy to fix.