Diesel Intern Jobs in California (NOW HIRING)

2026 Fall Engineering Intern
Location: [On-site - San Francisco] •
Term: Fall 2026 (Sept-Dec, dates flexible) •
Type: Full-time or part-time internship
About Estes Energy
Estes develops and manufactures zero-emission power systems that unlock true scale and performance for the electrification of commercial vehicle and equipment markets. Our goal is to democratize electrification - delivering powertrain solutions at better cost and performance than diesel, for both high-volume OEMs and next-generation newcomers.
We work on transforming advanced materials into battery systems for industrial and commercial applications, most of which runs on diesel today.
The problem we're attacking is real. Roughly 3.9 million barrels of diesel (5.8 TWh of energy) are burned every day in the U.S., mostly by commercial vehicles and equipment - emitting 1.66 megatonnes of CO₂, 353 kilotonnes of NOx, and 9.92 kilotonnes of SOx daily. We exist to move the needle on transitioning a century-old diesel-burning industry to electric.
The Role
We're a small, deeply technical team with ambitious goals, and our interns do real engineering work (not pet projects). As an Engineering Intern, you'll own a meaningful slice of a live project, work shoulder-to-shoulder with senior engineers, and see your contributions make it into actual systems. You'll reason from first principles, let data drive your decisions, and design with cost and scale in mind from day one.
What you'll do

• Contribute to the design, build, and test of components or subsystems within our power systems (mechanical, electrical, controls, battery, manufacturing, or systems engineering - depending on your focus)
• Develop and run experiments to test hypotheses, then turn data into decisions
• Build tools, models, fixtures, or analyses that help the team move faster
• Document your work clearly and present findings to the team
• Take ownership of a defined project and drive it to a measurable result by the end of your term

Who you are

• Pursuing a degree in Mechanical, Electrical, Chemical, Materials, Manufacturing, Systems, Material Science, Metallurgy or a related engineering field (or equivalent hands-on experience)
• Curious and rigorous - you ask "why," challenge assumptions, and get to the root of a problem before building up
• Comfortable with experimentation and data; you care about data integrity
• Able to take ownership, work independently, and collaborate directly and honestly
• Bias toward making things: hands-on project, lab, internship, research, or build-team experience is a plus

How we work - our core tenets
Reason from first principles • Only data can save us • Take deep ownership and excel at your craft • Design for cost and scale at every stage • Operate with good faith and accountability.
Compensation
Compensation is tailored to experience and role scope.
This is a paid internship based on-site at San Francisco.
Equal Opportunity
At Estes, we're building a team grounded in competence, character, and mutual respect, and we believe diverse perspectives are essential to solving the complex problems of our industry. We provide a workplace free from discrimination, harassment, and retaliation, and we ensure equal opportunity in all employment practices.