Senior Mechanical Engineer

Location: South San Francisco, CA

Department: Engineering

The Opportunity

This role is instrumental in the design, simulation, analysis, and testing of mechanical components for state-of-the-art electric vehicle powertrains. You will be hands-on across the entire product lifecycle—from initial concept to New Product Introduction (NPI). The ideal candidate possesses a robust understanding of mechanical engineering fundamentals, thrives on bringing theoretical designs to life, and is enthusiastic about pioneering innovative EV technology.

You will serve as a technical anchor, providing guidance on complex mechanical challenges and ensuring design integrity across the powertrain architecture.

What You'll Do

• Lead all aspects of design, validation, and manufacturing for EV battery systems across aircraft, off-road, and marine applications.
• Evaluate new manufacturing technology and equipment to enable scaling and continuous improvement of in-house battery production.
• Develop test plans and design validation methods for battery system failure modes.
• Perform trade off analysis and DOEs to optimize designs for performance and cost.
• Manage part and assembly lifecycles using SolidWorks CAD and PDM.
• Execute structural, thermal, and fluid simulations (SimScale), correlating digital results with physical testing.
• Collaborate with interdisciplinary teams electrical, software, systems, and project management team to deliver high confidence products.

Qualifications You Bring

• 5+ years of mechanical engineering experience, with a focus on multi-cell battery systems or high-voltage applications.
• A proven history of taking projects from concept through development, test, and certification into production.
• Proficiency in rapid-prototyping to create functional jigs and fixtures.
• Design experience using manufacturing methods such as; CNC Machining, Injection Molding, Sheet Metal Bending, 3D Printing.
• Joining methods, such as ultrasonic welding, wire bonding, laser welding, TIG, MIG, IP67 sealing methods.
• Experience evaluating and managing relationships with CMs and suppliers, including performing source inspections.
• Ability to review technical work and provide actionable feedback to team members.
• Ability to clearly communicate technical issues in succinct language with non-technical team members and stakeholders.
• BS, MS, or MEng in Mechanical Engineering.

What Makes You Stand Out

• A strong sense of ownership and the ability to thrive in a fast-paced, rapidly changing environment.
• Familiarity with aerospace or automotive safety certification standards.
• Experience managing technical data and revision control within PDM/PLM environments (e.g., SolidWorks PDM, Arena, or Teamcenter).
• Hands-on experience with high-voltage safety and battery management systems.
• Demonstrated knowledge in manufacturing processes.

Benefits & Compensation

We offer a comprehensive total rewards package designed to support your health, financial wellbeing, and work-life balance.

Financial Wellbeing

• Competitive Compensation: Base salary, sign-on bonus, plus an equity award.
• 401(k) Plan: Employer match up to 5% to help you save for the future.

Health & Wellness

• Comprehensive Benefits: Health, Dental, Vision, and Life Insurance, with 99% of premiums covered by the company.
• Paid Parental Leave: Fully paid leave to support your growing family.

Time Off

• Vacation & Sick Leave: Accrued vacation and sick leave.
• Company Holidays: Paid holidays in accordance with the company schedule.
• Flexible Leave: Unpaid personal leave options are available when you need them.

Additional Perks & Workplace Programs

We provide programs and experiences that foster connection, growth, and a supportive workplace culture.

Time Off & Wellbeing

• Bereavement Leave: 1 week fully paid.
• Jury Duty Leave: Up to 1 week fully paid.
• PTO Nomination Program: Recognize and reward your teammates with additional time off.

Growth & Safety

• Professional Development: Annual training budget to support your career growth.
• Safety Shoe Stipend: Company-provided support for required safety gear.

Office Life & Culture

• Collaborative Environment: We operate primarily on-site to foster fast-paced collaboration and execution. Hybrid flexibility may be available after an introductory period, depending on business needs.
• Team Outing Program: Department events including a half-day off and a company-sponsored allowance.
• Social Calendar: Weekly, monthly, and seasonal team-building events.
• Fuel Your Day: Regular catered team lunches plus a kitchen fully stocked with snacks and beverages weekly.

Commuter Benefits

• Travel & Charging: Uber Business access, free on-site EV charging, and more.

About the Company

About Stafl Systems

Battery Technology Solutions for a Clean Energy Future
Stafl Systems is dedicated to advancing all applications of lithium-ion battery technology to achieve a clean energy future. Since 2010, we’ve partnered with industry leaders to push the boundaries of innovation across electric vehicles, aviation, marine and consumer products. Our team brings proven engineering expertise across technical consulting, rapid product development, in-house prototype fabrication and battery pack manufacturing to solve some of the most complex challenges in today’s cleantech industry.