I've tracked battery degradation in the EVs we’ve driven during the past decade. The short answer is that our Nissan Leaf lost a lot, our Chevy Bolts not so much. Since switching to the Bolts, we’ve traveled nearly 70,000 miles on three different batteries. Each battery has lost about 5% of its capacity over 20,000 to 30,000 miles. Importantly, this modest capacity loss hasn’t affected how we use the cars or how far we can drive them.