2013 malibu
3 Answers
Have the alternator tested as well, should put out 14+ V
Here is a good link to show you how to test it. https://www.w8ji.com/battery_and_charging_system.htm
I have a 2013 Chevy Malibu w/ 2.5l and it will fluctuate between 12.5 and 15v regularly. I believe Chevy notes that in the operators manual that it is normal depending on what is running in accessories at any given time. if you battery is draining even when running for more than 20 minutes, you probably have an alternator issue or something is draining the battery when not being charged