Staff Mechanical Design Engineer – Electromechanical

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 About the Role Mainspring is seeking a Staff Mechanical Design Engineer to own the design of electrical enclosures and power electronics packaging for the Linear Generator. You’ll lead projects from requirements through design, review, testing, and release, working closely with EE, manufacturing, and suppliers, with potential for direct reports. Ideal candidates will have a strong combination of technical expertise and the drive to solve complex problems in a collaborative environment. Key Responsibilities

Own electrical enclosure and internal packaging design across the full cycle: requirements, prototyping, testing, iteration, tooling, and production release

Design busbars and the mounting of PCBAs, relays, contactors, fuses, and other electrical components

Drive thermal management, sealing, and vibration/shock robustness of electrical hardware

Define cable and wire routing, sizing, and connector/termination selection within the system

Partner with EE, manufacturing, NPI, supply chain, and suppliers to bring designs into production

Work with reliability and test teams to validate designs and iterate quickly

Lead root-cause and corrective actions for production, test, and field issues

Mentor and support junior engineers on design strategy and technical challenges

Travel to supplier sites occasionally as needed

Qualifications Preferred Qualifications

High-voltage / high-current system knowledge with UL or similar certification experience

Familiarity with harness and wiring standards such as IPC/WHMA-A-620 as applied to equipment wiring

Experience integrating or reviewing lithium-ion battery packs or modules

Background in EVs, energy storage, industrial electrification, power electronics, or ruggedized outdoor equipment

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.