Position Summary sonnen is seeking a Certification and Test Engineer to lead testing, compliance, and certification activities for battery energy storage systems. This role will collaborate with engineering teams, suppliers, and external laboratories to verify product safety and performance and support certification from development through production. Key Responsibilities Manage BESS certification and testing programs involving

UL 9540, UL 1973, UL

1741, and UL 9540A, as applicable. Develop compliance matrices, test plans, procedures, acceptance criteria, and technical reports. Coordinate certification submissions, laboratory testing, schedules, budgets, and resolution of findings. Perform or oversee electrical, thermal, environmental, performance, and protective-function testing. Analyze test failures, lead root-cause investigations, and verify corrective actions. Review hardware, firmware, and component changes for certification impacts. Maintain test records, certification documentation, and approved product configurations. Support production testing, certification audits, and safe laboratory practices. Required Qualifications Bachelor's degree in engineering or a related technical field, or equivalent experience. [3-5]+ years of experience in testing, certification, or compliance for BESS, batteries, or power electronics. Understanding of battery management systems, power conversion systems, electrical protection, and thermal management. Hands-on experience with laboratory instrumentation and data acquisition. Experience analyzing test results, investigating failures, and writing clear technical reports. Ability to interpret electrical schematics, wiring diagrams, mechanical drawings, and control-system documentation. Experience supporting third-party BESS certification and thermal runaway testing. Strong technical writing, troubleshooting, and project coordination skills. Preferred Qualifications Working knowledge of

UL 9540, UL 9540A, UL 1973, UL 1741, IEEE

1547 and other BESS-related standards. Familiarity with

NFPA 855, NFPA

70, and other codes. Experience with Python or similar software for test automation and analysis. Training in high-voltage electrical safety and battery laboratory procedures. Work Environment Office, laboratory, and manufacturing support, with up to [20-30%] travel to test laboratories, suppliers, and project sites.