Battery State-of-Health (SOH) Estimation from Coursera

This course can also be taken for academic credit as ECEA 5733, part of CU Boulder’s Master of Science in Electrical Engineering degree.

In this course, you will learn how to implement different state-of-health estimation methods and to evaluate their relative merits. By the end of the course, you will be able to:

- Identify the primary degradation mechanisms that occur in lithium-ion cells and understand how they work

- Execute provided Octave/MATLAB script to estimate total capacity using WLS, WTLS, and AWTLS methods and lab-test data, and to evaluate results

- Compute confidence intervals on total-capacity estimates

- Compute estimates of a cell’s equivalent-series resistance using lab-test data

- Specify the tradeoffs between joint and dual estimation of state and parameters, and steps that must be taken to ensure robust estimates (honors)

What's inside

Syllabus

How does lithium-ion cell health degrade?

As battery cells age, their total capacities generally decrease and their resistances generally increase. This week, you will learn WHY this happens. You will learn about the specific physical and chemical mechanisms that cause degradation to lithium-ion battery cells. You will also learn why it is relatively simple to estimate and track changes to resistance, but why it is difficult to track changes to total capacity accurately.

Total-least-squares battery-cell capacity estimation

Total capacity is often estimated using ordinary-least-squares (OLS) methods. This week, you will learn that this is a fundamentally incorrect approach, and will learn that a total-least-squares (TLS) method should be used instead. You will learn how to derive a weighted OLS solution, to use as a benchmark, and how to derive a weighted TLS solution also.

Simplified total-least-squares battery-cell capacity estimates

Unfortunately, the weighted TLS solution you learned in week 2 is not well suited for efficient computation on an embedded system like a BMS. As an intermediate step toward finding an efficient weighted TLS method, you will first learn a proportionally weighted TLS method this week. You will then learn how to generalize this to an "approximate weighted TLS" (AWTLS) method, which gives good estimates, and is feasible to implement on a BMS.

How to write code for the different total-capacity estimators

So far this course, you have learned a number of methods for estimating total capacity. This week, you will learn how to implement those methods in Octave code. You will also explore different simulation scenarios to benchmark how well each method works, in comparison with the others. The scenarios are representative of hybrid-electric-vehicle (HEV) and battery-electric-vehicle (BEV) applications, but the principles learned can be extrapolated to other similar application domains.

A Kalman-filter approach to total capacity estimation

In the third course of the specialization, you learned how to use extended Kalman filters (EKFs) and sigma-point Kalman filters (SPKFs) to estimate the state of a battery cell. In this honors week, you will learn how to extend those concepts to apply EKF and SPKF to estimating the parameters of a battery-cell model if the state is known, and also how to simultaneously estimate both the state and parameters of a cell model.

Capstone project

You have learned several different total-capacity estimation methods. Some of these methods work better than others in general, but any method is only as good as the data you give it. In this project, you will explore a different way to determine the "x" and "y" data you use as input to the total-capacity estimation methods.

Good to know

Know what's good

, what to watch for

, and possible dealbreakers

Examines state estimation, which helps battery researchers do modeling and simulation of battery cells

Taught by Gregory Plett, who are recognized for their work in battery engineering

Explores battery degradation mechanisms, which is highly relevant to modeling and simulation of battery cells

Investigates total-capacity estimation, which is standard in battery engineering

Involves Matlab, which is highly relevant to battery engineering

Has a strong reputation, as it is part of the Master of Science in Electrical Engineering at CU Boulder

Reviews summary

Battery management systems

Learners say this course, "Battery State-of-Health (SOH) Estimation" is a great course for anyone dealing with battery management and battery health. According to students, Dr. Plett explains complex concepts in an easy to digest manner with great coding examples. However, learners mention that some of the programming assignments are not as fruitful for those in research. Overall, students say this is a good course with a positive environment that has sound mathematical foundations.

Coding examples help apply course concepts.

"I like the offered code samples as they allow to understand the functions in more detail"

Course goes into mathematical depth.

"The course is going very deep in to mathematical models."

"Very good in-depth introduction to aging mechanisms of Li-Ion batteries, together with sound mathematical foundations."

Dr. Plett is a great instructor.

"I think the content and the way Dr. Plett teaches is amazing."

"It was very new to me, and very interesting stuff. It became even better with the instructor's skill."

Some programming assignments may be less useful for research.

"I only got 1 star off because of the programming assignments."

"I understand they were aimed for a wider audience but for those in research it wasn't as fruitful."

Activities

Be better prepared before your course. Deepen your understanding during and after it. Supplement your coursework and achieve mastery of the topics covered in Battery State-of-Health (SOH) Estimation with these activities:

Review the basics of Electrochemistry

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Understanding the principles of Electrochemistry will aid in understanding battery cell degradation.

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Read the provided chapter on Electrochemistry from a textbook
Watch an introductory video on Electrochemistry
Take a practice quiz or exam on Electrochemistry

Join a study group to discuss course concepts and work on assignments together

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Working with a team to discuss concepts will promote deeper learning and understanding, especially when working through assignments.

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Find a group of classmates to join
Meet regularly to discuss course material
Work together on assignments and projects

Practice estimating total capacity using different methods

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Practicing different methods of estimating total capacity will help solidify understanding and allow for quick comparisons of methods.

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Download the provided Octave/MATLAB scripts
Run the scripts using different sets of lab-test data
Evaluate the results of the different methods

One other activity

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Show all four activities

Write a technical report on battery cell health estimation

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Synthesize and communicate your understanding of battery cell health estimation techniques and their applications.

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Review literature and research papers on battery cell health estimation.
Summarize the key concepts and techniques in a well-organized report.
Discuss the advantages and limitations of different methods.
Identify potential future research directions in battery cell health estimation.

Career center

Learners who complete Battery State-of-Health (SOH) Estimation will develop knowledge and skills that may be useful to these careers:

Data Scientist

A Data Scientist collects, analyzes, and interprets data. They may work on a variety of data, including battery data. This course may be helpful for a Data Scientist who wants to learn more about battery state-of-health estimation. This knowledge can help them develop new and improved methods for battery data analysis.

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Software Engineer

A Software Engineer designs, develops, and tests software. They may work on a variety of software applications, including battery management systems. This course may be helpful for a Software Engineer who wants to learn more about battery state-of-health estimation. This knowledge can help them develop software that is more efficient and reliable.

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Mathematician

A Mathematician develops and applies mathematical models to solve problems. They may work on a variety of problems, including battery modeling. This course may be helpful for a Mathematician who wants to learn more about battery state-of-health estimation. This knowledge can help them develop new and improved battery models.

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Materials Scientist

A Materials Scientist studies the properties of materials. They may work on a variety of materials, including battery materials. This course may be helpful for a Materials Scientist who wants to learn more about battery state-of-health estimation. This knowledge can help them develop new and improved battery materials.

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Electrical Engineer

An Electrical Engineer designs, develops, and tests electrical systems. They may work on a variety of systems, including batteries. This course may be helpful for an Electrical Engineer who wants to learn more about battery state-of-health estimation. This knowledge can help them design systems that are more efficient and reliable.

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Physicist

A Physicist studies the fundamental laws of nature. They may work on a variety of topics, including battery physics. This course may be helpful for a Physicist who wants to learn more about battery state-of-health estimation. This knowledge can help them develop new and improved battery technologies.

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Chemist

A Chemist studies the composition and properties of matter. They may work on a variety of materials, including battery materials. This course may be helpful for a Chemist who wants to learn more about battery state-of-health estimation. This knowledge can help them develop new and improved battery chemistries.

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Quality Control Engineer

A Quality Control Engineer ensures that products meet quality standards. They may work on a variety of products, including batteries. This course may be helpful for a Quality Control Engineer who wants to learn more about battery state-of-health estimation. This knowledge can help them develop and implement quality control procedures for batteries.

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Automotive Engineer

An Automotive Engineer designs, develops, and tests vehicles. They may work on a variety of vehicle systems, including batteries. This course may be helpful for an Automotive Engineer who wants to learn more about battery state-of-health estimation. This knowledge can help them design vehicles that are more efficient and reliable.

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Battery Design Engineer

A Battery Design Engineer designs and develops batteries. They may work on new battery technologies or improve existing ones. This course may be useful for a Battery Design Engineer who wants to learn more about battery state-of-health estimation. This knowledge can help them design batteries that are more durable and efficient.

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Battery Systems Engineer

A Battery Systems Engineer designs and develops battery systems. They may work on systems for electric vehicles, renewable energy storage, or other applications. This course may be helpful for a Battery Systems Engineer who wants to learn more about battery state-of-health estimation. This knowledge can help them design systems that are more reliable and efficient.

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Battery Manufacturing Engineer

A Battery Manufacturing Engineer oversees the production of batteries. They may work in a factory or a research and development lab. This course may be helpful for a Battery Manufacturing Engineer who wants to learn more about battery state-of-health estimation. This knowledge can help them improve the quality and efficiency of their manufacturing processes.

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Battery Research Scientist

A Battery Research Scientist conducts research on new battery technologies. They may work in a university or a research lab. This course may be helpful for a Battery Research Scientist who wants to learn more about battery state-of-health estimation. This knowledge can help them develop new and innovative battery technologies.

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Battery Testing Engineer

A Battery Testing Engineer tests batteries to ensure that they meet safety and performance standards. They may also develop new test methods and procedures. This course may be helpful for a Battery Testing Engineer who wants to learn more about battery state-of-health estimation. This knowledge can help them develop more effective and efficient test methods.

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Battery Applications Engineer

A Battery Applications Engineer works with customers to help them select and use batteries for their specific applications. They may also provide technical support and training. This course may be helpful for a Battery Applications Engineer who wants to learn more about battery state-of-health estimation. This knowledge can help them provide better support to their customers.

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