Senior Mechanical Engineer

Critical Loop; Long Beach (CA); On-site; USD 100,000 - 140,000; Full time

Job summary

Critical Loop is looking for a Senior Mechanical Engineer in Long Beach, CA to lead the mechanical design of high-power battery energy storage systems and power conversion systems. This hands-on, on-site role demands leadership in all aspects from concept to deployment, ensuring robust engineering solutions in a fast-paced environment.

The ideal candidate will have over 10 years of experience and a BS in Mechanical Engineering, managing projects independently and contributing to a dynamic team focused on innovation in energy systems.

Qualifications

• 10+ years of experience in Mechanical Engineering.
• 3+ years in a production environment.
• Experienced in full product design cycles.
• Ability to manage own work without support.
• Proficient in generating mechanical drawings.

Responsibilities

• Lead mechanical design of battery energy storage systems.
• Own all project documentation and work instructions.
• Identify requirements in a multidisciplinary environment.
• Collaborate with fabricators to ensure specifications are met.
• Manage schedules and track design decisions.

Skills

Mechanical design of BESS

Production environment experience

3D CAD systems

Hands-on mechanical assembly

Problem-solving in fast-paced R&D

Education

BS in Mechanical Engineering or related field

Tools

SolidWorks

OnShape

Job description

About Critical Loop

Critical Loop is shaping the next generation of energy systems by building the integrated edge grid of the future. Specializing in advanced energy management and battery control systems, Critical Loop empowers businesses and communities to seamlessly unite distributed energy resources for faster, more reliable, and affordable grid access. With deep expertise in grid modernization and a passion for creating resilient, responsive energy solutions, Critical Loop drives innovation at the intersection of technology and energy.

Senior Mechanical Engineer

Critical Loop | Full-Time | On-Site, Long Beach CA

About Critical Loop

Critical Loop builds and deploys battery energy storage systems for commercial and industrial environments. We are expanding our production operations to increase capacity while keeping pace with regulatory compliance. This is a chance to help a growing company create the future of grid‑scale battery storage, leveraging the latest tools to minimize time to market.

We are a small, fast‑moving team. There is no mechanical engineering group here. You will be the senior mechanical voice on the team, working across hardware development, production, and field deployment.

The Role

We are hiring a Senior Mechanical Engineer to lead the structural, packaging, and thermal design of our high‑power battery energy storage systems, power conversion systems, and ground support equipment. You will own mechanical problems end to end, from blank‑paper concept through fabrication, validation, and field deployment.

This is a hands‑on, on‑site role. You will work alongside electrical engineers, field ops, and fabricators. You will not hand work off. You stay with the problem until it is solved.

What You Will Do

• Lead the mechanical design of BESS, power conversion systems, and ground support equipment, including large welded and bolted structures for outdoor and on‑road use
• Own all project documentation, CAD models, mechanical drawings, BOMs, and work instructions
• Work within a multidisciplinary environment to identify requirements and design systems that integrate cleanly with electrical and software teams
• Work directly with fabricators and contract manufacturers to get hardware built and assembled to spec
• Drive designs from blank paper through fabricated assembly, including managing schedules and tracking system design decisions
• Identify and resolve design risks proactively, before they become field problems
• Support field deployments and troubleshoot mechanical issues in the field when needed
• Set your own priorities and manage your own workload without waiting for direction

Must-Haves

• 10 or more years of experience with a BS in Mechanical Engineering or a related field with a mechanical engineering focus, from an accredited university
• 3 or more years working in a production environment

• Experience across at least 3 full product design cycles, including at least one as the responsible engineer owning design, BOM, and schedule tracking end to end
• Proven ability to take a design from blank paper through fabricated assembly independently
• Hands‑on experience with measurement, assembly, and fabrication of hardware
• Comfortable functioning as the sole mechanical engineer on a project, setting priorities and managing your own work without a mechanical engineering group to lean on
• 3 or more years with multiple 3D CAD systems; ability to work in SolidWorks and learn OnShape (no OnShape experience required, no certifications required)
• 3 or more years generating mechanical drawings per ANSI standards (GD&T certification not required)
• Able to ask questions, seek solutions, and operate effectively in a fast‑paced R&D and build environment

Nice-to-Haves

• Experience with assembly tooling, large weldments, ground support equipment, skids, trailers, lifting equipment, or other industrial hardware
• 3 or more years in thermal and fluid design for air‑cooled or liquid‑cooled electronic systems
• Experience with high voltage systems
• Background in both R&D and production environments
• Prior experience at an energy storage, EV, or industrial equipment company
• Familiarity with manufacturing processes including sheet metal, welding, machining, and plastics

Critical Loop is an equal opportunity employer. We're committed to building a diverse team and creating an inclusive workplace where everyone can thrive. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, disability, veteran status, or any other protected characteristic under applicable law.