I have a 2014 Chevy Malibu Lt eco and have had issues the past month and a half. Started off sputtering when I would be at a stop and try to push the gas. The check engine light came on. I took it to the shop that day and they ran a diagnostic and said my camshaft actuators were bad so I had them replace them. They installed aftermarket parts to cut down the cost of repair. Drove great but 31 days later my check engine light came back on and my battery volts were reading 12.3 while driving but no sputtering so I took it back to the same shop. They said my battery should be reading 13.8 to 14.3 volts while driving. Ran another diagnostic and said the battery was bad and only reading 9volts. It was the original battery 5years old so I bought a new battery and they installed it. The check engine light went off and drove fine for 9 days. Then I noticed when I stop at a light and the auto/stop shuts the engine off it sounds like it has a hard time restarting when I release the break to go. At that time my windshield wipers are so slow and my interior lights look dimmed. It use to be a smooth restart. I took it back to the shop yesterday and they ran another diagnostic and battery came back perfect,alternator came back fine. They even checked the secondary small battery in my truck that runs when the eco kicks on after the auto/stop engages and that was fine. They have no idea what wrong so I made an appointment with the dealership for February 18th (earliest appointment available) Ughhh! Just wondering if anyone has had this problem? Oh and while I’m driving if I put my air conditioner on full blast it pulls my battery volts up to 14.2 and doesn’t have any trouble starting back smoothly when it goes into auto/stop. Any feedback would be greatly appreciated. Sorry for the long post. 
That’s correct. Does your car meet this spec now?
While I’m driving it reads 12.3volts from my dash unless I blast my heat or air conditioning then the volts jump up to 13.8 to 14.3
That’s too low. Something wrong there. Your car probably has a computerized charging system. That means a computer determines from various sensors and driving history the current charging voltage based on how much juice it thinks the battery needs to be topped up. But 12.3 volts isn’t the correct number. Unless you are using a lot of electrical power elsewhere at the time, which doesn’t sound like its the case. You may have a faulty alternator. Suggest to check the alternator’s drive belt, maybe it needs to be replaced rather than the alternator.
The electrical power management for this vehicle is complicated, there are 6 modes of operation. In fuel economy mode the charging rate can be as low as 12.5 volts. In head lamp mode the charging rate is 13.9 to 14.5 volts so you should see the charging voltage increase after switching on the headlights. Your dealer’s technicians will be more familiar with your car than the tire and lube shop.
Thanks for the reply’s and information. I have an appointment with the dealership on February 18th to get it checked out. I’ll update this post with whatever they fine for future reference for anyone dealing with a similar issue. Thanks again! 
does voltage read 14v with a/c on and fans on low speed? or do the fans need to be on hi speed?
No. If the ac is on low speed it only reads 12.3 to 12.5. It has to be almost full max or full max ac to increase the volts to 13.8 to 14 range while driving . If I’m driving to long with the ac blast it will even read low 15 volts.