Dynamic Cycling – EV Batteries Hold Up Better Than Anticipated

A team of engineers from the SLAC-Stanford Battery Center believes that your EV batteries will last much longer than promised. This team released a report demonstrating that manufacturers have tested batteries incorrectly for years. Their study highlights how realistic driving patterns versus lab testing produce varying results. Here’s what you need to know.

In the past, EV battery testing was done in a lab. The industry standard required using a repetitive constant charge and discharge cycle. This method would be repeated until the battery degraded beyond use. Surprisingly, it turns out that this method of testing batteries isn’t accurate. The truth is your EV battery could last almost 40% longer.

Problems with EV Batteries Today

There are several concerns with EV batteries that need to be addressed to drive mainstream EV adoption forward. For one, EV batteries are one of the most expensive parts of the vehicle. On average, the battery accounts for 30% of the total costs. The costs of EV batteries continue to decline, but they still remain one of the biggest cost hurdles to large-scale adoption.

Source – EVBox

Replacement Woes

The cost of EV batteries affects both the price of the vehicle’s sale and its maintenance costs. For example, EV manufacturers like Tesla warranty their batteries for 8 years or 150K miles. This is less than the average EV battery life expectancy of 10-20 years. As such, older EV owners may find that their battery performance is not what they expected.

Cost-wise, replacing an EV battery can range from $5k to +$35K for a Tesla, meaning that replacing a battery can cost as much as a used vehicle in some instances. As such, considerable effort has gone towards extending battery life. Thankfully, it turns out that many EV batteries will far outlive their stated manufactured expectancy.

Dynamic Cycling – EV Batteries Study

A study¹ published this week in Nature Energy highlights how stop-and-go daily driving patterns extend the life expectancy of EV batteries. The engineers found that stop-and-go traffic, leaving your car parked for hours between trips, and other daily commute driving tasks extended battery life by about a third compared to lab tests.

Dynamic Cycling – EV Batteries Test

To test their theory, engineers came up with four types of EV discharge profiles. These profiles were based on daily driving patterns that were gathered from real driving data. They also set up some batteries using the traditional charge/discharge cycles as a test medium.

As part of their test, they used 92 commercially available lithium-ion batteries. The batteries were left to their respective discharge profiles for the last 2-years as engineers carefully monitored their degradation. They then took this data and created a machine-learning algorithm.

Dynamic Cycling – EV Batteries ML

The ML (machine learning) algorithm was a major step forward for the team as it combined past data, advanced controls, and active simulations. As such, it allowed them to lower research costs and run millions of scenarios across a massive array of dynamic discharge profiles. This data could then be used to further develop the ML algorithm.

Dynamic Cycling – EV Batteries Results

The engineer’s study revealed that the realistic discharge profiles lasted much longer than the original discharge testing profiles. On average, the tested batteries showed a 40% increase in life expectancy. It turns out that the hours your EV sits and the moment when you get on the acceleration are all beneficial to its life expectancy.

They also found a correlation between sharp accelerations and battery life. Unlike combustion engines, flooring in an EV is good for the battery and can enhance life expectancy. It allows the battery to cycle when used in conjunction with rest periods.

Time Matters

The engineers revealed that time plays a bigger in battery life than previously expected. For example, letting your battery rest for several hours can be beneficial to its life expectancy. The data revealed that daily drivers, who often got to a destination like work and left their car sitting for hours, gained additional battery life expectancy. This added battery life was due to the couple-hour rest period allowing the battery to cool off.

The data also revealed that letting your battery sit for too long is far more detrimental to its performance than thought. EV batteries can decay quickly when left sitting or not charged for a long time. The results determined that non-use is more dangerous to battery life than overuse.

Researchers

This study was led by engineers from SLAC-Stanford Battery Center. The team combined material science, engineering, computer science, and advanced ML algorithms to accurately map battery degradation based on driving patterns. Now, they seek to utilize their data to create more efficient and durable batteries.

Source – Stanford Report

Companies that Can Benefit from this Research

Many industries could see increased revenue due to enhanced battery life. This research could have long-reaching effects across multiple industries that rely on battery-powered products. From tomorrow’s self-driving cars to your smartwatch, longer-lasting batteries could benefit everyone. Here is one company that is ideally positioned to benefit from this study.

QuantumScape 

QuantumScape (QS ) was founded in 2010 to provide high-performance solid-state batteries to the EV market. The company’s founders Jagdeep Singh, Tim Holme, and Professor Fritz Prinz of Stanford University pioneered several technological breakthroughs including the creation of a ceramic separator that enhances battery life.

QuantumScape is a leading EV battery manufacturer with strategic partnerships with industry leaders including Volkswagen. Volkswagen pledged $100M to the company in 2018. In 2024, they unveiled an EV battery prototype that could handle 1000 charging cycles, demonstrating their progress.

Notably, the company’s stock has seen some drawbacks over the last few years. However, its positioning and proximity to releasing game-changing products have analysts convinced that QuantumScape has a bright future.

EV Batteries – The Key to Future Adoption

EV batteries are one of the most important aspects of adoption. This research highlights how recent advancements continue to improve battery performance and life expectancy. Additionally, this research demonstrates how tomorrow’s batteries will benefit from ML algorithms to ensure that they are the most efficient and powerful yet. For now, you have to give a salute to this team as their research could help power the batteries of the future.

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Study Reference:

^{1. Geslin, A., Xu, L., Ganapathi, D., et al. (2024). Dynamic cycling enhances battery lifetime. Nature Energy. https://doi.org/10.1038/s41560-024-01675-8}