A Tesla battery researcher has shown updated test results indicating batteries that last over 15,000 cycles or the equivalent of over 2 million miles (3.5 million km) in an electric car.
Last year, we reported on Jeff Dahn and his lab, who have a battery research contract for Tesla, releasing an interesting paper showing how the latest lithium-ion battery technology can produce batteries that would last 1 million miles in electric vehicles.
In a new presentation, Dahn discussed the updated test results of this new battery, which he hopes will become the new standard lithium-ion battery that new battery technologies are confronted with.
The scientist, who is widely recognized as a pioneer of lithium-ion batteries, referred to our article last year on their article and said it sparked enormous interest in this new battery chemistry and battery longevity.
They went on to test those batteries with some of them over 3 years of testing and over 1
Dahn now concludes that these batteries in a medium-range electric car would be able to last over 3.5 million km or over 2 million miles.
It also showed results based on different depths of discharge, meaning at what percentage of capacity the batteries are discharging before recharging, and showed that lithium-ion batteries perform very well after up to 15,000 cycles so far:
Most impressive is that batteries show little or no capacity degradation when discharged between 25% and 50% of their capacity, which is actually how most people use their cars.
On average, American drivers use their vehicles for less than 30 miles per day.
For example, with this battery in a Tesla vehicle with over 300 miles of range, you could use it to travel 30 miles per day and charging, on average, 70 to 80% each day, would result in very little or no battery degradation.
Considering that that would mean those batteries could practically last forever or much longer than a car’s actual useful life, Dahn raises the question: Do we really need such good batteries?
Tesla CEO Elon Musk said he expects to have batteries that would last more than 1 million miles for the automaker’s “robotaxis,” which will have a much higher utilization rate than consumer vehicles.
Musk has also mentioned in the past that long-life batteries are critical to other Tesla programs, such as Powerwall, Powerpack, and Tesla Semi electric vehicles.
Dahn also points out that these new long-life batteries could be useful in enabling vehicle-to-grid capabilities.
In the past, Tesla has been reluctant to allow owners to use batteries inside their cars to drain power into the grid due to the impact on battery longevity, but these new batteries would solve these problems.
Interestingly, Drew Baglino, one of Tesla’s key engineering leaders, recently said future Tesla vehicles will have bi-directional chargers that enable vehicle-to-network or vehicle-to-all technologies.
Dahn raised several other interesting potential 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 increasing their factory. They know they will need terawatt-hours of batteries for both energy storage and vehicles. It is an incredibly emotional time. “
Here’s Jeff Dahn’s new presentation in full:
Very interesting and impressive new test results here.
It’s particularly interesting as longevity isn’t something Tesla talked about a lot during the Battery Day presentation.
It has focused primarily on cost and size, but Tesla has been leading for a while now that they are making big improvements in longevity, and many of these improvements appear to come from Jeff Dahn’s lab.
Older Tesla vehicles have already shown only limited battery degradation and, in general, Tesla vehicle batteries already seem to hold up quite well, but it’s fascinating to think that in the near future the longevity could be so great as to enable new features and different cases of use.
As usual, Jeff Dahn isn’t disclosing if or when Tesla is implementing these changes, but with the company now making their own cells, I wouldn’t be surprised if Tesla 4680 cells featured insane longevity.
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