FYI: New research highlights the charging patterns and longevity of Lithium Iron Phosphate (LFP) batteries in electric vehicles.
Lithium Iron Phosphate Batteries: Cheaper, Safer but with Charging Caveats
Electric vehicles (EVs) powered by lithium iron phosphate (LFP) batteries are becoming increasingly popular worldwide. These batteries offer several advantages over traditional nickel manganese cobalt (NMC) batteries, such as being cheaper to produce, posing a lower fire risk, and providing greater longevity. However, LFP batteries come with their own set of challenges, as a new study funded by Tesla reveals.
The Downside of Full Charging for LFP Batteries
According to the study published in the Journal of The Electrochemical Society, LFP batteries degrade faster when frequently charged to a full 100%. Continuous charging at a high state of charge (SoC) induces negative reactions within the battery pack, leading to faster degradation. This finding contradicts the current recommendations from automakers like Tesla and Ford, who suggest fully charging LFP batteries periodically for better pack calibration and battery health.
LFP versus NMC: Key Differences
Unlike LFP batteries, NMC batteries—used in long-range models from manufacturers like Tesla—are generally recommended to be charged to only 80-90% to avoid premature capacity loss. High states of charge increase voltage and heat, which accelerates the degradation process in NMC packs. Conversely, automakers have traditionally recommended fully charging LFP batteries periodically to keep them healthy and ensure accurate range readings.
The Study’s Revelations
The recent study sheds new light on the inner workings of LFP cells at high SoC levels. It found that keeping these batteries fully charged leads to harmful compounds forming within the pack due to high voltage and heat. These compounds then deposit on the negative electrode, consuming lithium and accelerating degradation.
The researchers, including Dr. Jeff Dahn, a noted battery expert from the Tesla-funded Jeff Dahn Research Group, emphasized that higher states of charge speed up negative reactions in the electrolyte, consuming lithium inventory over time. Therefore, it’s better to avoid cycling the battery too often at high SoC levels.
Optimized Charging Practices
For everyday users, the practicality of maintaining an SoC between 0-25%, as suggested by the study, is low. It’s convenient to charge an EV to higher levels for various reasons, such as road trips, power outages, winter conditions, and more. Modern EV batteries are designed to withstand hundreds of thousands of miles, even with suboptimal charging habits. Automakers also back these batteries with long warranties to alleviate any concerns about longevity.
Practical Recommendations
While the study provides valuable insights into the longevity of LFP batteries, it mainly focuses on battery life rather than overall best practices for EV owners. To summarize the study’s findings:
- Full Charging: Accelerates degradation, particularly in LFP cells. Automakers recommend doing this occasionally for calibration but not daily.
- Frequent High SoC Cycling: Creates harmful compounds, particularly in LFP cells, leading to faster degradation.
- Lower SoC Maintenance: Extends battery life but is impractical for many daily use cases.
Conclusion
Despite these new findings, it’s still advisable to follow your automaker’s recommendations for everyday charging to balance battery health and convenience. Whether you’re driving a Tesla Model 3, a Ford Mustang Mach-E, or a Rivian R1S, understanding and adapting your charging habits can help optimize the performance and longevity of your EV’s battery.
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William Kouch, Editor of Automotive.fyi
This article has been meticulously reformatted and rewritten to present updated and engaging information while maintaining a focus on quality, readability, and accuracy. The insights provided aim to equip EV owners with practical knowledge for optimizing battery performance and longevity.
