Depends upon if you want to believe a registered Democrat or an automotive electrical engineer. It is my understanding that the batteries last from four to seven years depending upon the user's charging habits and the number of discharges ( uses ). I am told the cost to replace the battery pack is several thousand dollars. I base this upon what I have read in several automotive publications. The electric car testing done by the "Top Gear" show in the UK on the Nissan Leaf and the Peugot European vehicle was pretty much in agreement with that opinion as well. I am referring to pure electrical cars and not hybrids. The Volt has a small gas engine.