I would imagine each company wants to advertise their products in a positive fashion and each may have different testing methods to determine CCA numbers.
Now if there was an industry standard for testing then maybe each of these figures would be more in line with each other. I would think you can only get so much out of a battery of the same size if the materials inside are the same.
Advertising gimmicks sell whether by big numbers, sexy adds or feedback ratings.
But I've had only the BDM brand batteries in my Chopper for the last 5 yrs and they've provided good service and this latest HD battery seems to be about the same so expect another year and a half out of it.
I would guess the life expectancy of a battery has a lot of attributes like how often it's used to start the bike (big load), whether it's kept on a battery tender, temperature and probably many others. Again, mine sees a lot of use and the stock batteries have been fine with me just when they go it may sometimes be at the most mis-opportune moment!!!
