Mechanical Engineer IV – Battery Systems

Mechanical Engineer IV – Battery Systems

Please note that we are unable to provide visa sponsorship for this position.

Proper Voltage is unlocking the next generation of battery technology across robotics, data centers, and defense.

We're building intelligent battery systems that make advanced chemistries (sodium-ion, lithium-titanate, lithium-silicon) work in products that were never designed for them. Humanoid robots can upgrade power systems without redesigning their entire platform. Data centers get safer, cheaper backup power. Drones and autonomous vehicles get higher energy density without lengthy integration cycles.

If you want to work on hard engineering problems that matter this is the place.

• We are seeking a senior mechanical engineer to lead the mechanical architecture of battery modules and packs from concept through certification and into production. This role requires deep experience in battery pack development, with demonstrated exposure to UN 38.3 and UL 1973 compliance.
  This position will play a central role in ensuring our battery systems are structurally robust, thermally optimized, manufacturable at scale, and designed from day one to meet regulatory requirements.

• Lead Battery Mechanical Architecture
• Own mechanical design of battery modules and packs, including:
• Cell integration (prismatic, cylindrical, or pouch)
• Structural stack-ups and compression systems
• Busbars and high-current interconnects
• Define mechanical strategies for shock, vibration, and environmental durability
• Develop and optimize thermal management solutions (passive heat plates, TIM selection, airflow management, fan integration)
• Drive Certification Readiness
• Support and lead mechanical preparation for:
• UN 38.3 transport testing
• UL 1973 battery system certification
• UL 9540 / 9540A (as applicable)
• Translate certification requirements into mechanical design constraints, including creepage/clearance, enclosure integrity, and protection strategies
• Interface with third-party testing labs (UL, Intertek, TÜV, CSA) during investigations and reviews
• Validation & Testing
• Develop mechanical validation plans (vibration, drop, thermal cycling, abuse scenarios)
• Support root cause analysis during environmental and safety testing
• Improve design robustness based on test data and certification feedback
• Production & Manufacturing
• Drive design-for-manufacturability (DFM) for low-to-mid volume production
• Collaborate with contract manufacturers on:
• Assembly methods and fixtures
• Tolerance stack-ups
• Support transition from prototype builds to controlled production release
• Technical Leadership
• Mentor junior mechanical engineers
• Establish and reinforce best practices for battery mechanical system architecture

• Bachelor’s or Master’s degree in Mechanical Engineering
• 7+ years of experience in battery pack mechanical development
• Direct experience supporting battery systems that have passed:
• UN 38.3
• UL 1973
• Experience with industrial, stationary, or energy storage systems
• Proficiency in CAD
• Working knowledge of:
• High-voltage isolation principles
• Creepage and clearance requirements
• Structural FEA (shock and vibration)
• Thermal management in high-density battery systems
• Experience supporting transition from prototype to production

• Direct experience leading UL certification investigations
• Familiarity with UL 9540 / 9540A system-level testing
• Experience working directly with third-party certification labs
• Experience with sodium-ion or lithium-ion energy storage systems
• Exposure to IEC 62619 or other international battery standards
• Experience scaling products with contract manufacturers
• Salary range: $180, annually (commensurate with experience)
• Equity participation as part of total compensation
• Paid time off and company holidays
• Opportunity to play a key role in shaping next-generation energy storage platforms

Ready to work on power systems that matter? Let's talk.

The pay range for this role is:

180, USD per year (Carlsbad Office)