I have a 2011 Traverse LTZ. Had a starting issue in Dec 2019 so bought a Insterstate 850 CCA battery. Seems to be ok for about a week then starting issues. I have to put it on a 2 amp charger over night and then it is good for about a week. I turn off the auto lights off when starting and leave them off for short trips in town.The volt meter says 15 volts and I measured the voltage at the battery with a very good voltmeter at it registered 15 volts. Any ideas?