Lithium iron phosphate (LFP) batteries are cheaper to produce and more stable than traditional nickel-based chemistries.
A new study from a Tesla-funded lab found that LFP batteries degrade faster when fully charged.
Repeated charging at a higher state of charge increases negative reactions within a pack.
If you’re not driving your EV for extended periods, leaving the battery in a lower state of charge can help, as reduced voltage doesn’t harm in the long run. “Cycling near the top of charge (75–100% SoC) is detrimental to LFP/graphite cells. Our results show a correlation between the average SoC of battery operation and capacity fade rate, meaning that the lower the average SoC, the longer the lifetime…,” the study stated. “Therefore, the time spent cycling at high states of charge is critical to minimize.”
I wonder if Tesla will change their charging recommendation for those cars? I remember a few years ago, they changed their recommendation for non-LFP battery cars from 90% to 80% to maintain optimum health.
Watch the video at the link in the OP.
You can skip to 6 minutes-58 seconds. It covers the new report.
Operating you EV with state of charge of 75% to !00% is detrimental to your battery pack. If one’s objective is the prolonging the longevity of LFP battery pack; do not operate at 75% to 100% state of charge.
The lower state of charge one operates their EV the better for the longevity of the battery.
Obviously it is important to know what type of battery that ones EV has. Because charging practice for a NMC battery is entirely different from an LFP.
One final note this study was done at 40-50 degrees Celsius.
First caveat, the video is not by the authors of the study, It’s a uTuber interpreting the study. The chart shown is just a hand drawing, not actual data.
The study specifies how this happens on the most granular level. But kudos to YouTuber Jason Fenske of Engineering Explained for breaking it down for us.
True but it does not say how long that shorter lifetime is. Say with perfect charging the battery lasts 20 years while crappy charging only lasts 15 years. Does it really matter?
Modern EV batteries are temperature controlled. In a good EV the battery will not be charged at such high temperatures.
The linked article, LFP Battery Health Degrades At Full Charge, Study Finds ends with (emphasis added):
Still, it has some flaws. The study states that a 0-25% charging cycle elongates battery life. That seems pointless in terms of convenience for everyday users, especially if you don’t have a home or office charger and rely on public charging. The study focuses solely on battery longevity, not overall best charging practices. It leaves out what’s best for the broader EV-buying audience, like specific use cases, convenience, charging times and more. So it’s still advisable to follow your automaker’s recommendations.
A higher charge is beneficial in most cases, like road-tripping, during power outages if you need vehicle-to-home charging, during winter when range loss is accelerated or simply for the peace of mind. Plus, modern batteries last hundreds of thousands of miles even with bad charging practices. It’s one of the reasons brands offer long warranties on them. That’s not to diminish the study, which still accomplishes the all-important task of discovering more facets of what is still a relatively new technology.
Above all, the authors don’t recommend changing your charging habits. “How practical is it to cycle a battery cell in only low SoC ranges? There is clearly a tradeoff between useful capacity and capacity retention… It is not realistic to recommend cycling LFP cells between 0%–25% SoC only, because that is a waste of capacity.”
So? Are you saying only the authors of the study can understand their paper? And that someone with an appropriate engineering degree (like Jason) can’t?
If it means anything - and I think it does - the actual author of the study commented on this video, and praised Jason for his work explaining the study. If he thought there were significant deficiencies in the explanation, I have no doubt he would have mentioned them.
The study author also notes that he watched some of Jason’s videos while working on his own undergrad degree to get a better handle on his own understanding of various engineering topics. So I’d say your attempt to diminish Jason’s work here is based out of your own ignorance than any deficiency in the teaching.
Yes, he’s a YouTuber. Again, so? Making YouTube videos is a viable way to make a living these days. He is teaching engineering concepts via YouTube. Is that any different from teaching engineering concepts in a classroom or some other setting? In some ways, teaching very publicly like this forces you to be even more careful to get your facts correct. Anyone can watch the videos - including other experts in the field of study and experts in teaching (which is a separate skill unto itself). Also, see above on the study author’s comments.
Yes, the chart is hand drawn. Once again, so what? We all learn about graphs in school by drawing them by hand. The idea here isn’t to make overly detailed charts, it’s to teach a concept.
On the battery temperatures in the study, this is how longevity testing is done. Put things in difficult conditions and see how they perform. Pretty much all longevity testing uses techniques to accelerate aging and wear, then extrapolate those results out. Once again, buried in the YT comments is more from the author pointing out some of their testing details in the study that Jason didn’t have time to cover.
I would encourage folks to open up the video in YouTube and check out the comments. The one from the study author was the second comment when I looked. If it’s not there for you, look for comments that have responses from Jason. It’s one of those - which allows you to screen out most of them. Make sure to have comments sorted by “top comments” to keep this one near the top.