Thermal System Design Engineer

-; Brackley; On-site; GBP 40,000 - 55,000; Full time

Job summary

A battery technology start-up in Brackley is seeking a Thermal System Design Engineer to join their engineering team. The role involves developing thermal system designs for battery modules and packs, optimizing performance and safety in various applications. Ideal candidates will have a Bachelor's degree in engineering and at least 2 years of experience in thermal design. This position offers the opportunity to work in a fast-moving environment focused on electric mobility.

Qualifications

• Minimum of 2 years' experience in thermal design.
• Proficient in 1D thermal system modelling and analysis.
• Experience with 3D simulation tools, ideally using HyperWorks.

Responsibilities

• Develop 1D thermal system models for battery modules and packs.
• Provide thermal design input to teams.
• Conduct 3D thermal simulations (CFD) to validate designs.
• Define and manage thermal requirements in collaboration with teams.
• Develop design verification plans for thermal systems.
• Support design of experiments for thermal characterisation.

Skills

1D thermal system modelling

3D simulation tools

Thermal design

Interpersonal skills

Organisational skills

Education

Bachelor's degree in engineering

Tools

HyperWorks

Job description

Thermal System Design Engineer

IONETIC - who are we?

IONETIC is a battery technology start-up based in Brackley, just a few miles from Silverstone-the heart of British motorsport. We specialise in battery pack solutions for low-volume electrified applications, including buses, sports cars, and other vehicles. Our mission is to make electrification both possible and compelling for every vehicle OEM, by providing tailored, cost-effective battery packs with unmatched speed and flexibility.

By integrating proprietary software, mechanical design, and manufacturing technologies, into a single technology stack we call Arc, we deliver custom battery systems that meet a wide range of energy, power, and lifecycle requirements. Our chemistry-agnostic, scalable designs are built to accelerate the journey to net zero for our customers.

Working at IONETIC

IONETIC offers an exciting opportunity to be part of a fast-moving, innovative start-up that is shaping the future of electric mobility. With a strong order pipeline and growing demand for our technology, we're expanding our team to broaden our capabilities and scale our operations.

As an early-stage employee, you will play a key role in developing the foundational technologies and capabilities that will power the next generation of electric vehicles. Every employee at IONETIC takes on meaningful responsibility and is encouraged to contribute ideas, take initiative, and grow both professionally and personally in a supportive, collaborative environment.

Opportunity

We are looking for a talented and motivated Thermal System Design Engineer to join our growing engineering team. In this role, you will be responsible for developing thermal system designs for battery modules and packs using both cylindrical and prismatic cells.

You'll work closely with our mechanical, software, and manufacturing teams to create integrated thermal solutions that are configurable, efficient, and scalable within the IONETIC battery platform. Your work will play a critical role in optimising performance, safety, and longevity across a wide range of customer applications.

This is a hands-on, cross-disciplinary role with real influence over product development at an early stage in IONETIC's growth-ideal for an engineer who thrives in a fast-paced, collaborative environment.

Responsibilities

• Develop 1D thermal system models for battery modules and packs, supporting performance optimisation across various operating conditions.
• Provide thermal design input to mechanical and component teams, including sizing and specification of cooling plates, hoses, and system components.
• Conduct 3D thermal simulations (CFD) using the HyperWorks suite to validate and optimise thermal designs (training provided if needed).
• Define and manage system and component-level thermal requirements in collaboration with cross-functional teams.
• Develop and execute design verification plans to ensure thermal systems meet performance, reliability, and safety targets.
• Support design of experiments (DoE) for thermal characterisation and cell performance testing.

Skills and experience

• Bachelor's degree in engineering or a related technical discipline.
• Minimum of 2 years' experience in thermal design (experience from any sector will be considered).
• Proficient in 1D thermal system modelling and analysis.
• Experience with 3D simulation tools (CFD), ideally using the HyperWorks suite (training available if needed).
• Understanding of systems engineering principles, including the V-model.
• Familiarity with lithium-ion cell performance characteristics and their impact on thermal design.
• Interest in the electric vehicle sector and awareness of current battery technologies.
• Strong interpersonal and organisational skills, with confidence, enthusiasm, and a willingness to learn.
• Proficient in general computer use and capable of delivering clear technical presentations.
• Valid UK driving licence or suitable alternative for business travel.
• Willingness to travel both within the UK and internationally as required.