What he meant was that it could go for 1-2 years before needing to be replaced. It just needs to be recharged. The batteries that come in your car are hooked up with some thing called the alternator, which takes some of the energy coming from your engine and uses it to recharge your battery as you drive. Because the new battery is just sitting there, it isn't being recharged, and so it ran out of juice. It still works, it just needs to be recharged. I would inquire about a secondary or larger alternator to try and charge both batteries while you drive.