A Tesla battery researcher showed updated test results indicating batteries with a life of more than 15,000 cycles, or the equivalent of more than 3.5 million km, in an electric car.
Last year we reported on Jeff Dahn and his lab doing battery research for Tesla and published an interesting paper showing how the latest Li-ion battery technology can produce batteries that last 1 million miles in electric vehicles to have.
In a new presentation, Dahn discussed updated test results on this new battery, which he hopes will become the new standard Li-ion battery against which new battery technologies will compete.
Widely recognized as a pioneer in Li-ion batteries, the scientist referred to our article last year on his paper and said that it sparked massive interest in this new battery chemistry and battery life.
They continued testing these batteries, with some of them testing for three years and over 1
Dahn now concludes that in a medium-range electric car, these batteries could last more than 3.5 million km, or more than 2 million miles.
He also showed results based on different depths of discharge, i.e. to what percentage of the capacity they discharge the batteries before they are recharged, and it showed that the Li-ion batteries have so far worked very well after up to 15,000 cycles:
Most impressively, the batteries show very little to no capacity degradation when discharged between 25% and 50% of their capacity. This is how most people use their cars.
On average, American drivers use their vehicles for less than 30 miles a day.
For example, with this battery in a Tesla vehicle with a range greater than 300 miles, you could commute 30 miles a day. If you charge an average of 70 to 80% per day, there would be very little to no battery degradation.
Considering that these batteries could last practically forever or much longer than the actual life of a car, Dahn begs the question: do we really need batteries that are this good?
Elon Musk, Tesla CEO, said they plan to have batteries that last more than 1 million miles for the automaker’s “robotic axis,” which will have a much higher utilization rate than consumer vehicles.
Musk has also mentioned in the past the importance of long-life batteries to other Tesla programs like Powerwalls, Powerpacks, and Tesla semi-electric vehicles.
Dahn also suggests that these new super long-life batteries could be useful in enabling vehicle-to-grid functionality.
In the past, Tesla has been reluctant to allow owners to use the batteries in their cars to add power to the grid due to the impact on battery life. However, these new batteries would fix these problems.
Interestingly, Drew Baglino, one of Tesla’s lead engineers, recently mentioned that future Tesla vehicles will have bi-directional chargers that enable vehicle-to-network or vehicle-to-all technologies.
Dahn addressed some other interesting uses of batteries with extreme longevity and briefly commented on Tesla’s ‘Battery Day’ in the presentation:
“Tesla is moving forward at the speed of light. They are expanding their factory. They know that they will need terawatt hours of batteries for both energy storage systems and vehicles. It’s an incredibly exciting time. “
Here is Jeff Dahn’s new presentation in full:
Very interesting and impressive new test results here.
It’s especially interesting because Tesla didn’t talk much about longevity during the Battery Day presentation.
It was mostly focused on cost and scale, but Tesla has been guiding for some time that they are vastly improving longevity, and many of those improvements seem to have come from Jeff Dahn’s lab.
Older Tesla vehicles have already shown limited battery degradation, and in general the batteries in Tesla vehicles seem to be holding up pretty well already, but it’s fascinating to think that the longevity could be as great in the near future as it does new functions and other enables use cases.
As usual, Jeff Dahn doesn’t reveal if or when Tesla will implement these changes, but since the company now makes its own cells, I wouldn’t be surprised if the Tesla 4680 cells show insane longevity.
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