Mechanical Engineer II – Battery Systems

Engineering  |  Carlsbad, CA

Please note that we are unable to provide visa sponsorship for this position.

About Proper Voltage

Proper Voltage is unlocking the next generation of battery technology across robotics, data centers, and defense.

We're building intelligent battery systems that make advanced chemistries (sodium-ion, lithium-titanate, lithium-silicon) work in products that were never designed for them. Humanoid robots can upgrade power systems without redesigning their entire platform. Data centers get safer, cheaper backup power. Drones and autonomous vehicles get higher energy density without lengthy integration cycles.

If you want to work on hard engineering problems that matter — this is the place.

Job Overview

We are looking for an early-career mechanical engineer who is eager to grow in battery pack design and wants to develop hands-on skills in a fast-moving hardware environment. You'll work alongside senior engineers on real battery systems — contributing to CAD, testing, analysis, and manufacturing support from day one.

An interest or academic background in thermal analysis is a strong plus. We run active thermal test campaigns and simulation workflows, and this role is a great entry point for someone who wants to build depth in that area.

What You'll Do

Battery Mechanical Design

•        Support mechanical design of battery modules and packs under direction of senior engineers, including:

◦        Cell integration concepts (prismatic, cylindrical, or pouch formats)

◦        Structural components, brackets, and enclosure details

◦        Busbar and interconnect geometry

•        Create and maintain CAD models and drawings to support design reviews and prototype builds

•        Assist with tolerance stack-up analysis and DFM reviews

•        Help define and document mechanical interfaces across the assembly

Thermal Analysis (Preferred Interest)

•        Support thermal simulation setup and post-processing under guidance (SimScale, ANSYS, or equivalent)

•        Assist in evaluating TIM and interface materials — compile data sheets, summarize properties, and support comparison analyses

•        Help log and organize thermal test data from discharge campaigns and flag trends for senior review

•        Learn to correlate simulation outputs to physical test results

Testing & Validation

•        Support execution of mechanical validation tests — vibration, drop, thermal cycling

•        Assist with data collection, documentation, and test reports

•        Help track open issues from test findings and follow up on corrective actions

Prototyping & Manufacturing Support

•        Support prototype builds — attend build sessions, document assembly steps, flag fit/finish issues

•        Assist with fixture and tooling documentation

•        Communicate with vendors and CMs under direction to gather quotes, lead times, and capability data

Documentation & Process

•        Maintain clean CAD revision history and BOM entries

•        Write and update engineering documentation, test procedures, and work instructions

•        Contribute to design review materials and action item tracking

Required Qualifications

•        Bachelor's degree in Mechanical Engineering or closely related discipline

•        0–3 years of professional mechanical engineering experience (internships and co-ops count)

•        Proficiency in 3D CAD (Onshape, SolidWorks, or equivalent) — coursework projects are fine

•        Understanding of engineering fundamentals: materials, statics, GD&T basics, tolerancing

•        Ability to read and produce engineering drawings

•        Strong attention to detail and willingness to learn in a hands-on environment

Preferred Qualifications

•        Coursework or project experience in heat transfer, thermodynamics, or thermal systems

•        Any exposure to FEA or CFD tools — even academic (SimScale, ANSYS, SolidWorks Simulation)

•        Experience with battery-powered devices, EV systems, or energy storage in any context

•        Exposure to manufacturing processes — machining, sheet metal, plastics, assembly

•        Familiarity with UN 38.3 or UL safety standards (awareness, not expertise)

•        Experience supporting a physical prototype build from CAD to assembled hardware

Compensation & Benefits

•        Salary range: $95,000 – $130,000 annually (commensurate with experience)

•        Equity participation as part of total compensation

•        Comprehensive healthcare benefits (medical, dental, vision)

•        Paid time off and company holidays

•        Structured mentorship and a clear path to grow into an ME III role

Ready to work on power systems that matter? Let's talk.

The pay range for this role is:

95,000.00 – 130,000.00 USD per year (Carlsbad Office)