just because they're new doesnt mean they might be defective also.

dont count out the fact that any, or any combination of the new parts may also be bad also.

this happened to me when i had the optima yellowtop batteries.

first one died within a year and i was in denial like "its a yellow top, its supposed to live forever". i got a replacement, which died a month or so later. so i checked my car for all sorts of stupid things, but it turned just to be the yellow tops. once a dry cell loses its charge, thats it, its a goner. i think they have been discontinued because there were so many failures.