A lifetime warantee on batteries would be easy actually. how many people would take the time to send it in and get a replacement rather than just pay 10 bucks or less for a new one and get it quicker. I, honestly, would get the replacement, but many people are not patient enough to bother with it, nor are many people paying enough attention to even realize that they have such a warrantee. I bet less than 5% of their customers who have had a faulty battery have actually called on them to replace it. It's just how people are... buy a new part rather than deal with the annoyance of a warrantee for something so cheap. Using a tire company as a comparison isn't fair because we're talking $100ish for a tire over $10 for a battery. And this community is so small, especially compared to drivers who need tires, that offering such a warantee probably doens't set them back at all, but instead propels them further ahead because of it.
Just my 2 cents from how I perceive marketing.
Just my 2 cents from how I perceive marketing.