I replace batteries when they start the slow-crank-of-death IF the car does this. Most of mine had this to some degree.
A Ford Taurus SHO - big motor, tight engine bay, would murder batteries. Trip to the store, fine, trip home NOthing and it could not be jumped. Internal short, I expect from heat, since it loaded the jump vehicle hard, heated up the jumper cables and still wouldn’t start. Since it was the wife’s car, that meant I pick up a replacement battery on the way to rescue her and the car.
Because of this thread, I went out to the garage to check the battery on my 2002 Miata. It’s date stamped March 7, 2004. That’s consistent with the car’s history, because I bought it from someone who kept it parked on the street in San Francisco, and decided to sell it after someone slashed the top and ransacked the car, stealing the owners manual and the battery, because that’s all there was to steal. He realized it was crazy to own a soft top car in the city. I keep the car in a garage, and the temperature is very steady there, between the low 40’s and the upper 70’s. Combined with very few electronic devices to drain the battery, it should last a long time. 12 1/2 years so far and it starts every time, and looks spotless, stored under the floor covering of the trunk.
I was sorry to hear they vandalized Camp Chase in Columbus. I get to Columbus quite often but have never seen the lady in white in the cemetery. Hope the spirits followed the vandals.
Really though, 16 years is a little extreme but congratulations, you saved a couple hundred dollars in batteries but still you coulda got stalled at any time.