---
title: 'Test Engineer, Product Qualification at Mainspring Energy'
canonical: 'https://feeny.ai/job/test-engineer-product-qualification-mainspring-energy-menlo-park-ktw960qq6va4'
type: 'job'
last_seen: '2026-09-07'
---

# Test Engineer, Product Qualification at Mainspring Energy

- **Company:** Mainspring Energy
- **Location:** Menlo Park, CA
- **Compensation:** $108k–$124k
- **Work type:** onsite
- **Posted:** 2026-03-19
- **Last confirmed live:** 2026-09-07
- **Apply:** https://jobs.lever.co/mainspringenergy/b0b4b682-5e3d-41d1-ac6c-4d2303b1fd71

## 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 Our Linear Generator is a sophisticated, automated, and integrated system spanning a wide range of engineering disciplines including thermodynamics, mechanical, electrical, software, and controls. We are looking for a driven, highly motivated Product Qualification Test Engineer to join our test engineering team.

## Responsibilities

- Perform hands-on work and operate our Linear Generator units, working closely with our end of line team
- Qualify cores, units to be shipped to customers sites in our facility in Menlo Park, and support contract manufacturing
- Outline and develop testing processes & infrastructure to scale up product qualification tests
- Generate, analyze and automate data reports on new units, and work with all engineering teams to identify and root cause issues
- In collaboration with our manufacturing testing team,  participate in the development of new automation processes to enable the scaling up of qualification testing in manufacturing

## Qualifications

- Master’s degree in mechanical engineering, electrical engineering, physics, or equivalent with 3+ years of applicable experience
- Experience of conducting experimental hardware projects plus if in the context of product qualification or manufacturing test engineering
- Experience in project management
- Proficiency in programming in at least one language (e.g. Python, MATLAB)
- Detail-oriented and comfortable working in a fast-paced environment
- Enjoy working in interdisciplinary teams

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.

## About Mainspring Energy

## Company Overview
- **One-liner**: Mainspring Energy designs and manufactures fuel-flexible linear generators that provide low-emission, dispatchable onsite power for utilities, data centers, and industrial customers.
- **Entity Type**: Private (Series F)
- **Headquarters**: Menlo Park, California, United States
- **Founded**: 2010
- **Founders**: Shannon Miller

## Core Business
- Primary industry: Electric Power Generation
- Target customers: B2B – utilities, data center developers, enterprise, industrial
- Mission statement: "Redefining how local power is delivered to capacity constrained companies and communities" – enabling clean, reliable, and fuel-flexible power.

## Products & Services
- **[Linear Generator (LGen)]**: A flameless, fuel-flexible generator that converts gaseous fuels (natural gas, biogas, hydrogen, propane) into electricity with near-zero NOx emissions. Modular (0.25 MW per unit), fast-ramping (0-100% dispatchable), 46% electrical efficiency (LHV). Standardized 2.5 MW configuration (10 units). Suitable for grid-parallel or grid-independent operation, microgrids, and balancing renewables.

## Market Standing
- **Valuation/Market Cap**: Not disclosed (private company)
- **Key Metrics**: Annual revenue $117M (latest fiscal year); total funding $813M; 407 employees
- **Notable Investors/Partners**: General Catalyst (led Series F, 2025, $258M), Lightrock (led Series E, 2022, $140M), BloombergNEF (grant), and others.
- **Growth Signals**: Powering the largest U.S. EV truck charging depot; >1 GW of capacity trusted by Fortune 500 companies and utilities; headcount growing +3.4% YoY; job postings up +121.4% YoY (62 active openings); recently expanded into data center market.

## Competitive Advantages
- **Fuel Flexibility**: Single generator can seamlessly switch between natural gas, RNG, hydrogen, and propane without hardware retrofits.
- **Near-Zero Emissions**: <1.5 ppm NOx (0.05 lb/MWh) – meets stringent air quality standards.
- **Dispatchability**: 0-100% load following, grid-independent operation, capable of firming renewables.
- **Low Maintenance**: Only two moving parts, no oil changes, modular design reduces downtime.
- **High Efficiency**: 46% electrical efficiency (LHV) across all scales.
- **Fast Deployment**: Factory-built, skid-mounted units enable rapid installation.

## Strategic Focus
- Scaling manufacturing and deployment to meet growing demand from data centers and utilities.
- Advancing hydrogen and biogas compatibility to support long-term decarbonization.
- Expanding standardized 2.5 MW configurations to lower installed cost and accelerate timelines.
- Building a diverse, cross-disciplinary team to drive innovation in power generation.

## Why Work Here
- Culture of inclusion, respect, and collaboration across engineering, operations, and field teams.
- Emphasis on growth: "We invest in your growth because progress requires people who keep getting better."
- Hybrid/Remote options: headquarters in Menlo Park, manufacturing facilities, and remote field service roles.
- Active hiring across engineering (mechanical, electrical, software), operations, supply chain, and field service.
- Competitive salary ranges (e.g., Engineer ~$107k, Controls Engineer ~$109k, Manufacturing Engineer ~$91k) plus benefits.
- Diverse talent origins from Tesla, Stanford, Apple, SunPower, and other top clean energy companies.

## Sources
1. [mainspringenergy.com/company](https://www.mainspringenergy.com/company)
2. [mainspringenergy.com/careers](https://www.mainspringenergy.com/careers)
3. [jobs.lever.co/mainspringenergy](https://jobs.lever.co/mainspringenergy)
4. [linkedin.com/company/mainspringenergy](https://www.linkedin.com/company/mainspringenergy)
5. [mainspringenergy.com/product](https://www.mainspringenergy.com/product)

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