SW Engineeer - HIL Testing

Contract (6-9 months, with potential conversion to full-time) | On-site, California | Confidential Client

Our client is a fast-growing energy storage technology company bringing next-generation battery systems to market. They're looking for a Software Engineer to help build out the test infrastructure that verifies their Battery Management System (BMS), the electronics that monitor and control the battery, before it ships to customers.

This role sits at the intersection of software and hardware. You'll be building Software-in-the-Loop (SIL) and Hardware-in-the-Loop (HIL) test systems, simulation environments that let engineers safely and repeatedly test how the battery's control electronics respond to real-world conditions, without needing a live battery hooked up for every test.

• Build out SIL/HIL test infrastructure from the ground up, including wiring, schematics, and instrumentation

• Write device drivers that let software communicate with lab test equipment (instruments that inject voltages, read sensor data, and simulate real operating conditions)

• Build the software framework that allows test engineers to write and run automated test cases on top of that infrastructure

• Work closely with firmware and test engineering teams to verify product safety and performance ahead of major product launches

• Experience building or working within SIL and/or HIL test systems

• Strong software engineering background, particularly writing drivers or interfaces for hardware/test instrumentation

• Proficient in Python

• Comfortable working independently in a fast-moving, ambiguous startup environment

• Firmware development experience

• Background at an automotive, EV, or battery technology company

• Familiarity with C

• Familiarity with UL 1998 or similar firmware safety/testing standards

• Location: On-site, California (relocation not provided)

• Type: Contract, with strong potential to convert to full-time for the right fit

• Interview process includes a technical screen, a Python coding exercise, and an on-site panel with the team

You should be proficient in:

• HIL Testing
• SIL Testing