Battery life and camera age?

Just been wondering about something battery related.

Obviously, batteries lose power with age and become less effective. And given that I use, among others, a Sigma DP3 Merrill, I'm very familiar with poor battery life. I have four batteries in total, and now two of them (the original ones) are literally useless. They can't hold a charge, and the two which can will give me maybe 30 or 40 shots before packing it in. Luckily they're small and cheap to replace.

What I was curious about is whether there are other factors, like the connectors (if that's the word), or something else within the electronics, which also affect battery life.

I was checking out (with half a mind to buy; it was an extremely good deal) a very well used Nikon D3 last week, and I happened to notice that the battery life indicator was on "3", i.e. "pretty well used, gonna be time to replace it soon"). I'm guessing that it was the original battery.

Assuming I were to put a brand new battery in it, and run it through a few cycles, would it still provide the number of shots that it would have in a brand new D3 from 2007 (which, I believe, was hundreds and hundreds, even into the thousands, on a single charge)? Or will the age of the camera effect the performance of even a new battery?

I know some of you guys and girls still use D3s and cameras of that age - any experiences?

I was astonished to read that the expected battery life of the D3s is 4200. And that should be what you could expect on an old one with a new battery. It is the number of times that it is charged that limits the life of a battery. I expect 200-300 times. I have an even older D90 and its battery life remains about the same as when it was new.

Can I have more info on this?

I struggled wit your question at the beginning… Then when I thought about it more I kinda found myself asking something similar…

I used a Pentax *ist DS with AA rechargeable batteries… I never used the autofocus on my camera… And the batteries held a charge for ages… I still have and still use the original batteries I used with that camera and we're talking batteries that are over 10 years old… Now i'm asking if the 'load' and how much pressure we put on the power source affects it's longevity…

I know other photographers that struggle to get 2 years out of rechargeable batteries and within my circle i'd say the average lifetime of a rechargeable battery is around 5 years which is pretty decent…10 years is outstanding.

Of course connectors can break over time but the age of the camera has nothing to do with battery life.
As they're used any number of times, as you've said, batteries will become less and less useful… It's the battery's age, not the camera's age.