Prove what? The OP said it was guaranteed to fail within 8-10 years. That number is clearly made up since the base warranty is already 8 years, and we already h

Prove what? The OP said it was guaranteed to fail within 8-10 years. That number is clearly made up since the base warranty is already 8 years, and we already have examples of batteries that are older keeping up just fine. Its OP's responsibility to prove their claims. But they can't, because they are making up numbers