> I agree. Once a year, I discharge each of our car batteries then 
 > recharge. Typical lifetimes are three to six years.
I never discharge [lead-acid] batteries on purpose, but they do get a bit of 
cycling in normal usage. I seldom have a car battery last less than 4 or 5 
years.
I'm beginning to believe that those sealed batteries like the Champion and 
Gates (so-called 6-pack) units are the way to go. There's a pair in my 
backhoe and one in my truck, and both are going on downright elderly. And 
both are abused: the backhoe sits for literally months without being run; I 
charge the batteries and away she goes. The truck gets it in its head to not 
start now and then and it gets cranked excessively. Yet it bounces back for 
more. These 3 Champion sealed batteries are over 8 years old. These are some 
sort of gel-cell construction because they claim that the batteries can be 
mounted in any position without harm.
The pair of sealed "maintenance free" batteries on my sawmill engine went 
over 10 years before needing replacement. I know what Ian's tagline says 
about sealed batteries ("you wouldn't weld the hood of your car shut, would 
you?"), but my experience has been very positive.
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