We have a 2010 Enclave and other than the original factory battery, we have had 2 failures within 2 years of a dealer installed, new Delco battery. Is this a thing or am I just unlucky with Delco batteries?
AC Delco is not known to have good batteries. The best I can get out of them is roughly 3 years, while reputable aftermarkets such as Duralast or Interstate should last between 4 to 6 years. In my opinion the key is to drive at least 20 minutes without stopping to fully charge a battery at least once every other day, or even on a daily basis. Quite contrary to popular believe, sitting at idle does not "charge" a battery, it may, at best, supply enough current to keep the car running.
Similar issue with my 2017 Enclave. At 17 months the battery simply died right after I had driven it 20 miles. Dealer replaced it, new one lasted less than one month. I was told by the dealer rep that the guys had put the wrong battery in as a replacement--too small. No issue since a year ago.