Which battery, the 12v battery or the hight voltage battery.12v 100.00$ should last 3 years if from dealer or a good aftermarket battery interstate id my preference 4.5-6 years but should be replaced at 5 yrs regardless.The main high voltage batteries, A Guess 6K - 8K and should last 8-10 years but looks like some manufactures batteries are not making it as long. And you need to go back to the dealer if it's the second. Those battiries can kill you.Cost lots of doe to be green huh! Hope it's the first.