Battery Failure Analysis

15 Jan 2021

Getting to the Root of the Problem

Due to the complex nature of batteries, determining the cause of a failure of a battery-powered device may require expert knowledge across several scientific and engineering areas. Failure analysis is the process of collecting and analyzing data to identify the root cause of a failure. The findings are often used to determine corrective actions to prevent failure of similar products, improve the design of future products, or address liability claims.

Battery-powered devices can fail for a number of reasons: battery/cell failure, device malfunction (external to the battery), or failure of the battery management control system integrated into the battery itself or through separate circuitry designed into the device. A battery or cell failure may be performance (e.g., the lifetime of the battery is not up to the specification), safety (e.g., a cell/battery overheating), or leakage related (e.g., the electrolyte starts to leak from the cell container). The challenge of battery failure analysis is to unambiguously identify the problem's root cause.

Failure analysis involves the use and application of a variety of tools the selection of which requires years of experience and technical expertise. It often involves investigating a complex combination of possibilities and conditions. The process ultimately points toward a specific root cause. In essence, a battery failure analysis involves data collection, analysis of the data, and proving that the true root cause has been found by demonstrating the ability to create and eliminate the problem at will.

A thorough failure analysis includes the following steps:

• Situation appraisal: A general term describing the need to fully understand the failure and what is being requested. Nearly all situation appraisals follow the same natural progression and involves questioning the client to learn as much as is possible about the failure itself, circumstances surrounding the failure, and any other pertinent background information. A situation appraisal is critical to best focus efforts and avoid the cost and time which might otherwise be consumed if many dead-end analyses are performed.
• Examination of batteries and cells: Depending on the failure, battery type and findings of the situational appraisal, this may include a physical examination, electrical characterization, performance characterization of cells, non-destructive X-ray, examination of the battery management system and control circuitry, dissection of cells and analysis of cell construction, and chemical analysis.
• Simulation of suspected faults and misuse by testing: For performance-related analyses, it is important to know what the performance deficit looks like. Discharge testing, pulsing, cycling (for rechargeables), leakage testing, and accelerated aging are all within the performance umbrella that may need to be verified. If you cannot characterize or replicate the performance deficit in the test lab, finding its root cause will be extremely difficult. A complicating factor is that there may be a limited supply of the "poor" performing cells available for the failure analysis. For safety-related analyses, it is important to know how a cell or battery behaves during a specific abuse or misuse. Forcing the cell or battery to failure by going beyond standardized tests will give important information about possible failure modes such as the degree of severity.
• Manufacturing audits: If the root cause is a known or suspected manufacturing defect, an audit of the manufacturing process is essential. It is essential to uncover the depth of a manufacturer's knowledge base and to pay close attention to manufacturing steps of interest – those related to the failure or defect. It is sometimes surprising the level of follow-up questioning needed to dig deep enough to uncover an issue.

Battery failure analysis can provide important information to help ensure higher quality products and secure a company's brand reputation. Learn more about the process and Intertek's approach to battery failure analysis in our white paper.