A follow up . . . . I had my battery tested and there was nothing wrong with it. I was told that I just need to drive it more to keep it charged up. I have a 2021 Yukon Denali which has a ton of accessories and I know there is some parasitic drain on the battery when it is parked. The dealer said it's not good to let it set for days at a time without driving it as the battery can be drawn down. This is all the more reason why I don't plan to use parking mode. It's just another drain on the battery which is already strained.
If your battery has spent a lot of time mostly discharged in freezing weather, or extremely hot weather, it’s guaranteed to not be operating at full capacity, regardless of what those useless battery testers say.
Automotive starting batteries aren’t designed to be heavily discharged, in fact most will sustain some minor damage / lost capacity w/ one single heavy discharge event.
Deep cycle batteries are designed differently w/ thicker plates / grids to handle discharge cycles. Starting batteries aren’t.
Battery testers at shops are mostly useless for determining battery health & capacity outside of a completely failed battery that obviously needs to be replaced. They’re a rudimentary battery internal resistance pass/fail checker to determine whether the battery can likely provide enough cranking amps to turn over a starter, they don’t check for capacity, they don’t check battery health, & they don’t give measurement for battery’s ESR.
Instead of driving more, use a quality battery charger instead & connect it once a week overnight, & whenever you aren’t going to drive for a while. It takes hours of charging to fully charge a decent sized automotive battery. A 2021 Denali will have a big battery, you’d need to drive for hours to fully charge it. Either way, you’ll find you need to replace the battery soon due to degradation from being in a fairly deep discharge state for a while.
