An FDA inspection netted a Wallace, Idaho devicemaker a warning letter, after the investigation revealed quality violations that led to adulterated defibrillator batteries.

Specifically, the agency discovered during its Nov. 6-9, 2018 inspection of Zeller Power Products that the firm didn’t have design validation documentation for its automated external defibrillator battery.

The design validation documentation was needed to justify the battery’s five-year shelf-life. The company also failed to validate software used on the battery’s circuit boards.