Testing Battery Life

[MaxPower]

I have read that as a battery gets older, it's internal resistance increases and the output/usable charge time becomes less and less. Is this correct?

What would be the 'starting' internal resistance and what would be the 'all used up' internal resistance. Would one just use a multimeter to test this resistance?

 

[Ryedan]

I have not tried this, but I've seen the same process described a few times; How to measure internal resistance.

I've got a few old batteries that have a lot of voltage drop. I think I'll be doing this myself soon

 

[MaxPower]

Thanks, that thread has some good info in it. I'll give that a shot.