Design Review
Factory Audits
Failure Analysis
Batteries
CTIA Certification
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Battery Pack Incident Investigation
When a battery fails in a manner that results in electrical malfunction, thermal damage, case rupture, or combustion, a number of questions typically arise:
- Was the failure induced by external forces, such as severe mechanical damage or excessive heat exposure?
- Was the failure the result of cell, protection circuitry, or pack design?
- Was the failure the result of an internal cell fault or a pack manufacturing flaw that was not detected by the quality control procedures put in place by the manufacturer?
- Does the failure represent a random occurrence or is it an early sign of a developing trend?
- If a product cell is warranted, which manufacturing lots should be recalled?
Differentiating between the potential causes of any failure can be difficult, particularly when the failed product or system has been heavily damaged. Based on numerous lithium-ion battery failure analysis investigations, Exponent has developed a systematic investigation approach that has proven effective in identifying the particular causes of any given failure and developing recommendations for corrective action as appropriate. This method may include techniques such as:
- Damage pattern documentation and analysis
- Battery pack/cell disassembly
- X-ray examination
X-ray of an incident battery cell
- Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy (SEM /EDS) analysis
- Material and metallographic examination
Cross section of a battery case
- Computed Tomographic (CT) scanning
CT scan of an 18650 battery cell
- System analysis and testing
- Charge/discharge testing
- Battery protection circuit analysis and testing
- AC adaptor electrical testing
- Printed circuit board (PCB) propagating fault analysis
- Contact resistance analysis
- Infrared camera thermal measurements
- Burn injury assessment (thermesthesiometer testing)
- Failure replication testing
- Statistical analysis of failure rates and exposure (risk analysis)
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