Walmart battery died after a little over 3 years, so manage to get the car started and take it back to the store where purchased. It was a "Maxx", so I have them replace with the same. Then when I get the bill I find that there are 2 choices: (1) Get about $30 credit on the old battery, which was in the "prorate" period, but then the new battery will only be covered by the remainder of the old battery's warranty, or (2) no credit from the old battery, the new battery gets its own new warranty starting today. Obviously I go with #2. I was told all battery warranties work this way, though somehow I'd never run into this before. My one previous experience with replacing a WM battery, which was about 6 years ago and a different state (CA), but same car and also WM "Maxx" battery, they did give me prorated credit on the old battery when I got a new one, and the new battery started a new warranty period.