Senior Staff Mechanical Engineer - Electromechanical

Job Description

Job Description

About Mainspring

Mainspring Energy manufactures and delivers fuel-flexible, low-emissions local power solutions that rapidly add new capacity and deliver reliable, affordable, and sustainable electric power. The company began commercial shipments of its Mainspring Linear Generators in 2020 and today has hundreds of megawatts in advanced development and field operations for leading Fortune 500 companies, data centers, and utilities. Mainspring also partners with global energy leaders including AEP, NextEra Energy Resources, Schneider Electric, and more.

The core values that ground our work, guide our decisions, and connect us together:

• Pragmatic Optimism
• Excellence without Ego
• Proactive Collaboration

Job Overview

Mainspring is looking for a Senior Staff Mechanical Engineer — Electromechanical to lead the design and integration of electrical enclosures, busbars, and cable systems for our next-generation energy platforms.

This is a highly visible technical leadership role focused on solving difficult real-world engineering problems across power electronics packaging, harsh-environment durability, manufacturability, and system integration. You’ll help shape core product architecture while working on systems deployed across demanding operating environments ranging from coastal and desert conditions to future megawatt-scale applications.

We’re looking for an engineer who understands how electrical and mechanical systems behave in the real world — and can drive robust electromechanical solutions from concept through production.

Responsibilities

• Lead the design and development of electrical enclosures, busbars, cable assemblies, and integrated electromechanical systems
• Drive packaging decisions balancing thermal performance, vibration durability, EMI considerations, creepage/clearance, manufacturability, serviceability, and cost
• Own hardware through the full product lifecycle including concept development, prototyping, validation, production launch, and sustaining engineering
• Partner closely with Electrical, Reliability, Manufacturing, Test, NPI, and supplier teams to develop robust hardware solutions
• Solve challenging environmental durability problems involving corrosion, outdoor deployment, thermal extremes, and vibration-heavy operating conditions
• Lead root-cause investigations for field and test failures and drive corrective actions into production
• Mentor engineers through design reviews and technical leadership on complex problems

Qualifications

• BS or MS in Mechanical Engineering or related field
• 12+ years of experience designing electromechanical hardware systems
• Proven experience designing electrical or electronic enclosures through production release
• Strong background in sheet metal design and mechanical-electrical integration
• Experience packaging electrical components such as fuses, contactors, relays, PCBAs, busbars, cables, connectors.
• Experience in designing systems such as inverters, controllers, fuse systems, batteries, or other power electronics. 
• Understanding of thermal management, vibration, environmental durability, grounding, creepage/clearance, and EMI-related packaging constraints
• Experience supporting validation, testing, manufacturing launch, and sustaining engineering
• Proficiency with SolidWorks and PLM systems

Preferred Qualications

• Busbar design experience
• HV power systems experience
• Cable harness and routing design experience
• Experience with corrosive or outdoor deployment environments
• Familiarity with FEA tools such as Ansys
• Background in EVs, power electronics, energy systems, industrial equipment, or ruggedized hardware systems

This position is onsite at our Menlo Park HQ . The salary will be adjusted to reflect local market conditions based on employee location as well as the experience of the employee. Along with base salary, Mainspring offers pre-IPO company equity through Restricted Stock Units (RSUs) + benefits.

Before you apply, a quick note on your resume
We care about the substance of your work and want to make sure we learn as much as we can about your design experience. To help us evaluate your experience accurately, please ensure your resume includes:

• What you actually built or worked on — name the real product, subsystem, or hardware (not just "components" or "systems"). "Redesigned the bracket mounting the compressor to reduce vibration failures" tells us far more than "designed mechanical components."
• What you personally did , separate from what your team did. If you contributed to a group project, tell us your specific role and contribution.
• The engineering fundamentals you applied — tie your skills (CAD, FEA, GD&T, thermal/fluid analysis, testing, etc.) to the actual problem you used them on, rather than listing them as standalone skills.
• What happened as a result — did it pass validation/testing, resolve a failure, ship to production, and if so, at what volume or scale (prototype quantity, low-rate production, high-volume manufacturing)? This helps us understand whether your experience is with one-off/prototype hardware or product that shipped at scale.

One more thing: please don't feel obligated to keep your resume to one page. If accurately describing your relevant projects and contributions takes more space, that's completely fine — we'd rather see the detail than have you compress or omit meaningful work to fit a page limit.

Thank You!

Does your experience not meet all of our posted requirements? Studies have shown that some people are less likely to apply to positions unless they meet every listed requirement. At Mainspring, we are committed to building a diverse, inclusive, flexible, and collaborative environment, so if you want to help us transition the world to clean and affordable electricity, and don’t meet all posted requirements for a particular role, we’d still love to hear from you. Mainspring can sometimes be flexible enough to shift responsibilities for the right person, or otherwise identify open or upcoming roles that may better fit your professional background.

In more traditional words, Mainspring Energy, Inc is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, or protected veteran status and will not be discriminated against on the basis of disability.

This compensation and benefits information is based on Mainspring Energy's estimate as of the date of publication and may be modified in the future. We generally do not negotiate on salary once we have made an offer. The level of pay within the range will depend on a variety of job-related factors that may include location, relevant prior experience and/or education, or particular skills and expertise. New hires joining the company tend to be paid within the starting base pay range noted above, with opportunities to increase pay over time based on development of additional skills, competencies, and company-specific knowledge.

We may use artificial intelligence (AI) tools to support parts of the hiring process, such as reviewing applications, analyzing resumes, or assessing responses and identifying potential inconsistencies or verification signals in application materials based on available information. These tools assist our recruitment team but do not replace human judgment. Final hiring decisions are ultimately made by humans. If you would like more information about how your data is processed, please contact us.