Have heard the same ...but there really are some major differences between batteries. The cell seperators, how porous they are, how resistant to pore clogging, the plate densities, the plate lattice (upon which the lead and lead oxide plates are deposited; ie. the 'metal screen' that gives the plate strength)- case quality, metallurgy of the plates (they have additives). Remember how bats used to always have their water levels checked ? No more- additives to the plates allow the hydrogen and oxygen release by charging to be 'recombined' and maintain the cells water level. Other differences also - just named a few.
My rule has always been to buy the highest CCA (cold cranking amp) battery in the largest size that will fit in the bat compartment. That (amd tying 'em down properly to minimize vibration which is a big killer) seem to yield max life for me.
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