You think thr 2500 year reference was a MATH ERROR? You truly have no sense of humor.
You probably never heard the show about the guy who bought a new car and put a bra on it to protect the paint. He was told by someone that high speed driving with the bra could cause the bra to flutter and damage the paint. He made a weekly 1 hour expressway trip and he was taking it off then putting it back on after the trip. To correctly refasten the bra took him a half hour and he was getting tired of it and did the brothers have a fix?
They assured them they did. The told him to go to the nearest Kmart, look for a parking place between two big 2 door American cars ant take his time, have coffee and whatever horrible concoction the served for food. He said, but what am I buying? They told him he didn’t have to buy anything, he could go out to his car which now had door dings on both sides and just get on with his life.
That is from my memory and not word for word, but you get the idea…I hope.
The most people, I will admit is conjecture. However I’ll argue that it’s based on at least reasonably sound observations and simple math : amongst the collection of people I know or have known, a large fraction turn to me for “car help”, because I’m the guy with the tools. These people span pretty much the entire middle-class economic range of the USA. In 40 odd years of doing this, I have not met a single one of them that changes their battery before it starts to show its age with hard starts in cold weather, etc.
If my 40+ year sampling of middle-class folks is even close to representative of typical middle-class behavior, it seems quite unlikely that those worse off, are changing their batteries more frequently. The people in upper-middle-class income range and below, make up the largest segment of the population, in both the US and world-wide.
Taken together, simple math says that the average battery rolling down the road, is somewhere close to the middle of its lifespan, ergo a few years old and at reduced capacity compared to new.
Unfortunately, I don’t know of any way to get at that data, unless maybe the battery manufacturers would be willing to divulge the age of returned cores (I will say, when I’ve noticed the rack of returned cores in a shop, their condition supports my conjecture )
I think the most solid evidence we can get, is that a variety of places that have car-age statistics, all point to the average age of a car on the road, being around 12 years. This means that the average car has been through at least one, probably multiple battery changes, and that the average car is outside any warranty-covered “total maintenance” program that would replace the battery on a schedule, rather than when it showed signs of needing to be changed.
As such, unless there’s some compelling reason to believe that people would voluntarily change their batteries before they show signs of needing to be changed, it’s reasonable to assume that the majority of cars are wearing batteries until they show noticeable signs of decline. Noticeable signs of decline, from the driver’s perspective, are much further down the road, than reduced capacity for the purposes of extended run-time on accessories.
The only thing that would invalidate the analysis on the face of it (other than some force that would convince people to spend money on a new battery when their old one seems to be working perfectly fine) would be if we were subject to a program like used in Japan, where cars are essentially mandatorily removed from the road, inside the lifespan of their first battery.
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