Senior Reliability Engineer

Catalyzing a cleaner future.

ESS is a globally recognized leader in sustainable energy storage and is consistently identified as one of the most innovative and exciting technology players in energy storage. It is poised to be one of the fastest growing energy technology companies in the world, with projects already across 4 continents and an upcoming public offering. The ESS vision is about enabling the decarbonization of the grid by enabling us to achieve up to 100% of our electricity from clean, sustainable renewable energy.

These are ambitious goals, and we are pursuing them with passion. At ESS, we are leading the energy transition, creating the sustainable energy solutions of the future to help individuals, businesses and communities change energy into lasting value.

ESS is seeking a motivated and versatile Senior Reliability Engineer to join our team. As a Reliability Engineer focused on ESS's Energy Base product, you will have primary responsibility for the reliability assessment, validation, and design guidance of ESS's core electrochemical components, including iron flow battery stacks, electrochemical rebalancing cells, and fluid interfaces. You will own the reliability lifecycle-from concept and design through development testing and analysis, manufacturing, and field operation-ensuring exceptional performance at every stage.

In this role, you will investigate failures using physics-of-failure methods and physical testing to accurately predict component and system robustness. You will then translate these insights into design and architecture improvements that prevent recurrence and continuously enhance product reliability, as well as creating system level reliability estimates. You will act as a reliability advisor to system and hardware design teams, helping assess the suitability of off-the-shelf components for ESS's unique operating environment and long service-life requirements.

What you'll do at ESS:

Core Component Reliability

• Own reliability engineering of our iron flow battery stacks and rebalancing cells.
• Identify dominant degradation and failure mechanisms (electrochemical, chemical, mechanical, thermal, and environmental).
• Develop physics-of-failure models to guide accelerated life testing, operating limits, and design tradeoffs.
• Define reliability requirements and targets for core components based on field usage conditions, duty cycles, and costing models.
• Design and execute validation plans to determine expected operating lifetimes at different specification ranges.
• Lead teardown and failure analysis of lab-tested and field-returned components.
• Partner with relevant engineering functions to translate failure analysis findings into design changes, updated requirements, and validation improvements.

System-Level Reliability

• Support system-level reliability analyses, including fault trees, reliability block diagrams, and DFMEA.
• Help integrate component-level reliability data into system reliability models and predictions.
• Analyze field data from deployed systems to identify trends, emerging risks, and opportunities for design improvement.
• Serve as a reliability advisor to design teams evaluating off-the-shelf (OTS) components, helping assess whether commercially available parts are fit for long-duration, grid-scale energy storage applications.
• Review OTS component data sheets, qualification reports, and life-test data to evaluate assumptions, margins, and applicability to ESS operating conditions.
• Translate ESS-specific duty cycles (electrical, thermal, mechanical, environmental, and chemical exposure) into clear reliability risks, gaps, and recommended validation or derating strategies.
• Provide guidance on when additional testing, screening, or supplier engagement is required before deployment.

Supplier & Cross-Functional Engagement

• Define and communicate reliability requirements for critical suppliers supporting battery and electrochemical components.
• Review and challenge supplier life-test data, assumptions, and acceleration models.
• Support supplier corrective actions related to reliability issues.
• Maintain and grow internal reliability guidelines, best practices, and lessons learned.

What you bring to the table:

Minimum Requirements

• Bachelor's degree in Materials, Mechanical, Electrical Engineering, ora related field.
• 10+ years' experience in reliability engineering, component development, or failure analysis (flexible for strong candidates).
• Strong understanding of accelerated testing methods, governing equations, and physics-of-failure for a range of failure mechanisms.
• Solid foundation in applied statistics and reliability statistics (e.g., Weibull analysis, Maximum Likelihood Estimation, Bayesian methods, Monte Carlo simulation).
• Experience with failure analysis techniques (e.g., optical microscopy, SEM, C-SAM, X-ray, cross-sectioning, EDX, etc.).
• Proficiency with reliability engineering analysis tools such as the Relia Soft platform.

We'd love to see

• Experience with batteries, flow batteries, fuel cells,…