In 1984 I visited a Johnson Controls plant in South Carolina and they produced car batteries. While walking down the assembly lines I saw at least 10 different brands including Die Hard and Insterstate, different cases but the same internals...
Not always, in the mid 1960's Dad worked for ESB (now Exide) in Kansas City. ESB was also OEM for the local Ford plant. One day he overheard a worker carping (he used much saltier language) about why such an inferior car company needed such a superior battery. This was just after tar tops ended, batteries were rated by amp hours, not this nutty cranking amps stuff, and how many lead plates they could cram into a case.
By the mid 1970's I worked for JC Penny in the auto center when they introduced the JC Penny lifetime battery. Dad is STILL getting freebies from Firestone. Anyway, there were two vendors, AC/Delco (flat top) and Gould (two big rectangular caps) We had FAR less troubles (replacements) with the AC Delcos. I gave up on Johnson Control products, Interstate, Optima, Duramax Gold and have been using AGM AC Delco Professional series of late. Pretty well satisfied with the AC Delco products. Corrosion and warranty issues just don't exist anymore. 2ยข
