Battery posts are getting almost like oil posts…Lots of anecdotal evidence, lots of outdated thinking and “old crotchety-ism” (get off my lawn!!) because cars just aren’t what they used to be!
Back in the day, a $40 battery (about $260 in today’s dollars) with 350 CCA, powered by a 45 amp alternator lasted 3 years and anybody could replace one. You didn’t even need to reset the clock… it was broken, anyway, they always were. The biggest electrical draw was the blower motor, headlights and maybe the wipers.
Fast forward 60 years. Batteries and electrical systems in modern cars have undergone significant changes to the detriment of the battery. Now the battery has 800 CCA, costs $90 (less in than back in the day!) to as much as $400 (yeah, a bit more) is charge-managed by a computer with a 180 amp alternator and is used as an energy reservoir for electric power steering, heated seats, ABS/TCS/ESP pumps, big amplifiers, stop-start, electric AC compressors and hundreds of electrical gizmos spread through the car. As such, the cars computer needs to know a LOT more ABOUT the battery so it needs to be programmed to any new battery. And they still can last 6 years if taken care of.
My 2014 Audi battery looks original. The last battery in my truck lasted 6 years. Both 100% in Florida. The Optima battery in my Honda was 9 years (3 in Florida) and I let it go flat at least 4 times and still was fine when I sold the car.