Electric vehicles powered by lithium iron phosphate (LFP) batteries are becoming increasingly popular due to their cost-effectiveness and stability compared to traditional nickel-based chemistries. A recent study funded by Tesla has shed light on the degradation of LFP batteries when fully charged, highlighting the negative impact of repeated charging at higher states of charge.
LFP batteries are known for being more affordable to produce and safer than nickel-based batteries. They are commonly used in entry-level electric vehicles like the Tesla Model 3, Ford Mustang Mach-E, and Rivian R1S. Automakers recommend periodically charging LFP batteries to 100% to calibrate the pack and maintain battery health. However, the recent study suggests that fully charging LFP batteries can accelerate degradation due to high voltage and heat within the pack.
The study found that harmful compounds are created in the battery when fully charged, leading to the deposition of these compounds on the negative electrode. This process consumes lithium and causes degradation over time. Keeping the battery in a lower state of charge when not in use can help prevent this degradation, as reduced voltage does not harm the battery in the long run.
Dr. Jeff Dahn, a renowned battery researcher who leads the Tesla-funded Jeff Dahn Research Group, was among the authors of the study. The lab has played a significant role in advancing battery technology and understanding the intricacies of different battery chemistries. While the study emphasizes the importance of cycling LFP batteries in lower states of charge, it acknowledges the trade-off between useful capacity and capacity retention.
Despite the study’s findings, it is still advisable to follow automaker recommendations for charging practices. Higher states of charge can be beneficial in certain situations, such as road trips, power outages, or winter driving. Modern batteries are designed to withstand hundreds of thousands of miles even with suboptimal charging practices, thanks to long warranties offered by manufacturers.
In conclusion, the study highlights the need for a balance between practical charging habits and battery longevity. While cycling LFP batteries in lower states of charge can prolong battery life, it may not always be convenient for everyday users. It is essential to consider specific use cases, convenience, and charging times when determining the best charging practices for electric vehicles.