First off, thank you for what you do. You have given me so much information on cars!
I have a Chevy Cobalt, coupe, manual transmission, year 2010. I live in Austin, TX. My car cannot start anymore.
Here is what I first noticed: It took a second more to start (when it was starting). It was basically a delayed start and then would be a very short start. Also, I noticed the diagnostics took a lot longer to run. Took maybe about 30 secs down the road until it was complete. I know this because my tire pressure is a little low and the indicator on my dash would let me know.
Then the car would take even longer to start. I would turn the key and could hear it struggling, but would eventually turn on. I did notice one thing though, if I was out for the day driving around the car would start easier. The most trouble I experienced was when I started my car first thing in the morning. I decided to finally try to find some solutions. Took my car to Autozone to check the battery, it was fine. Reading at 12V. Then I decided to take my battery back again, but I took it out of my car this time. Wanted to see if there would be a difference, but no. Still reading at 12V. This is when the man at AutoZone suggested the alternator. Did my research and decide to do a small test. Put the battery back in my car, put the key in and turn the car on idle. I notice that all my electronics worked (radio, air, lights, headlights, etc.) Then I just decided to wait... I noticed my headlights got dimmer and the air/fan slowed down. Then I decided to try and start my car. When I try I hear a lot of clicks extremely fast! So, I stop. I put the car back in idle and now no lights are on in the car except the radio clock. The fan/air is barley blowing, headlights are barley on, and I had no dash lights at all.
This makes me believe that the alternator is not charging the battery efficiently. What do you think, Scotty?