Know Your Battery

Originally published by Joshua Gordon,, December 13th, 2017

The battery pack of an electric vehicle (EV) is a crucial concern to consumers. What is the actual range of an EV? How long will it take to charge? And will typical consumer behaviors have to change to adopt an EV? Below we focus on the anxieties surrounding battery life and degradation, as well as take a look at current developments in both the EV and EV battery markets.

Battery Life

A heated debate currently exists around the potential duration of EV battery life. EVs have not been in circulation long enough for researchers to gather comprehensive data on lifetimes. Indirectly, a indication of battery life may hide in the warranties currently available from manufacturers. Tesla, for example, offers an 8-year warranty, the world’s best-selling Nissan Leaf, with a 30kWh battery, also provides an 8-year warranty period.

It is perhaps too early to estimate the actual life cycle of a lithium-ion battery, as the data just isn’t available. However, researchers at The Electrochemical Society found that partial discharge can increase battery life substantially.  For example, with a 100% discharge cycle (most aggressive), batteries can typically last between 300-500 cycles. However, take the discharge rate consistently to 50% and the life expectancy can improve considerably to 3 to 4 times. Luckily for we EV owners, it is uncommon to need a full charge.

According to a presentation delivered by the American Chemical Society, it is quite reasonable to estimate the lifetime of a battery pack of an EV to be up to twenty years. That’s good news when you consider that some estimates put the average life expectancy of a new car at about eight years.


Battery degradation in electric vehicles leads to capacity fade, thereby shortening the vehicle’s possible range.

The lack of battery degradation data for analysis sparked Maarten Steinbuch and Merijn Coumans to create a study in the field. What they achieved was the first of its kind. In cooperation with the Dutch-Belgium Tesla Forum, they created a public spreadsheet entitled ‘MaxRange Tesla Battery Survey’ that allows Tesla drivers to post information about their remaining battery capacity. The project began in 2015, as of 29th November 2017, 396 users where participating

Plug In America has a similar survey going on and it has found similar results to the Tesla data. Most drivers are retaining over 90% of original battery capacity. Outliers are seeing even more impressive results – the shuttle service Tesloop reported in September that one of its Model S cars had passed the 200,000-mile mark, having lost only 6% of its original battery range.

Are lithium-ion batteries the preferred mix?

Most of the EVs today run on lithium-ion batteries, the same technology that powers smartphones and laptops. Lithium-ion batteries have fallen in price by 80% in just the last six years, according to McKinsey & Company. However, an EV battery pack is still relatively expensive. Chevy Bolt’s battery pack costs over $15,500over 40% of the EV price tag.

Economies of scale will help drive the cost down further. Tesla’s claims that once its Gigafactory is at full capacity, it will be able to reduce the battery costs a further 35% to $125kWh. Other manufacturers are following suit with new battery factories and this ramp up in production could be the catalyst to bring EVs into the market at competitive price points.

Fuel-cells are similar to batteries in that they produce electricity without combustion or emissions. However, like gasoline vehicles, they can run for over 300 miles on one tank, and refuel within minutes. At the Los Angeles Auto Show, Toyota announced they are building a renewable hydrogen generation station at the Port of Long Beach, California that will produce 1.2 tons of hydrogen fuel per day and 2.35 megawatts of electricity. While the hydrogen fuel-cell is currently seeing just a fraction of market share, and lithium-ion batteries are the preferred power source, a desire exists to explore the opportunities in this unique technology.

Battery technology will see tremendous changes over the next few years, from storage capacity to chemical formulations to greatly lowered costs per stored kilowatt hour. Read this interesting article about alternative battery configurations currently being studied.