Battery Life

“So how much for a new battery?” That’s a question I get surprisingly often. No one asks me how much a new gas tank for my gas car would cost. Both store energy until the car’s engine needs it. I think the question comes from the fact that everyone has replaced batteries before. Batteries in toys, cell phones, laptops, etc. are replaced regularly. So, people tend to expect to have to replace the batteries in electric vehicles (EVs). Even worse, the lithium-ion batteries like those in the ever popular cell phones, laptops, tablets and EVs like our Leaf can be quite costly.

The batteries in an EV last longer than those in less expensive consumer products because of the systems put in place to protect them. The battery in our Leaf is expected to last 10-12 years. Nissan guarantees it against defectives for eight years. I’m happy to get ten years of life from a car so those figures work for me. I’m planning to replace the battery in our Leaf as often as I plan to replace the gas tank in our Camry – never.

So is that it? Not quite.

The amount of charge which a lithium-ion battery can hold gradually drops over years of use. Yup, they are not perfect. That means that the range of our Leaf will also gradually drop each year. “How fast is gradually?” you might well ask. It depends.

Nissan has a second warranty on the battery which provides some protection against this drop in capacity. They will replace the battery if it drops below 65.5% of its original capacity before five years of use (before eight years for the 2016 Leaf). That may not sound great. Even worse is that some Leaf owners have already experienced this level of battery degradation, especially those in very warm climates. That said, I doubt that many Canadian owners of a new Leaf, especially those in cooler climes like the Maritimes, will have to worry about this.

The batteries of all EVs will fade over time but the actual amount will be far less for our Leaf than that implied by Nissan’s warranty. Here’s why:

Canada is colder. Heat is the number one enemy of battery life. Most of the early Leaf battery failures and capacity losses happened in hot places like Arizona. Most of the time the temperature an EV battery has to endure in Canada is pretty benign except during summer heat waves. We do experience a temporary drop in range during our frigid winter days but, as a bonus, that winter chill also helps preserve the long-term capacity of the battery.

Few fill-ups. Keeping a battery fully charged or close to fully charged for an extended period can speed up battery capacity loss. We avoid this by normally waiting until night-time to charge and even then only charging the Leaf up to only 60-70%. That’s plenty of power for a day’s running around.

Driving style. Lee and I are pretty laid back drivers, for the most part. Slow starts, gradual stops and safe highway speeds. All of these reduce stress on the battery, and on the driver too!

The battery in our Leaf is currently at 94% after 18 months. Only a 6% loss makes me feel pretty optimistic since battery capacity loss typically starts fast then slows. Of course, eventually the capacity will drop so much that the Leaf won’t be able to comfortably make the trip from New Maryland to Saint John. That will be sad but the majority of our driving which is around town will remain unaffected. As mentioned above, we currently only charge the battery to 60-70%. Even a battery with only 60-70% of its capacity left will be quite fine for us. Based on our current experience, I’m expecting it will remain above 80% after 10 years of use in Fredericton. I’ll update you on the progress of our battery’s health/capacity as time goes on.

Another thing to keep in mind is that the current generation of the Leaf (2011-2016) relies on air cooling of the battery. Other EV manufacturers (Tesla, GM, Kia, etc), which started producing cars after the Leaf came out, use more effective methods based on liquid cooling. I anticipate that the next generation Leaf, which is expected in 2018, will also use liquid cooling for its battery. All of these EVs should do a much better job of retaining of battery capacity.

Finally, I know that we’ll have replaced our gas car with a 300+ km range EV long before we can’t get to Saint John in the Leaf. Remember my prediction for an affordable long range EV by June 2018? I’m still banking on it.