20 Battery Engineer Interview Questions and How to Answer Them

Battery engineer interviews mix electrochemistry fundamentals with applied design judgement. Here are 20 questions that recur across Indian battery employers, with the answer pattern interviewers are listening for.

Fundamentals (8 questions)

• What's the difference between energy and power density? When does each matter more?
• Why does cycle life depend on depth-of-discharge?
• Explain the SEI layer and how it grows.
• What's a CC-CV charging profile and why is it standard?
• How does temperature impact lithium-ion aging?
• What's coulombic efficiency and why does it matter?
• Explain Peukert's law and where it applies.
• What's the role of the separator in a Li-ion cell?

Design judgement (7 questions)

• How would you size a pack for a 250 km city-EV with 80% range retention at year 5?
• Walk through your thermal-strategy choice between air, liquid cold-plate and immersion.
• When would you pick LFP over NMC?
• How do you decide on parallel vs series cell configuration in a module?
• What's your worst-case cell-imbalance design budget?
• Walk through your venting and TR-propagation containment plan.
• How do you specify a BMS for a new pack design?

Process + regulatory (5 questions)

• What does AIS 156 require, and which clauses changed last year?
• Walk through your DV / PV plan structure.
• What's your incoming-cell inspection protocol?
• How do you triage a field-return pack with capacity-fade complaints?
• What documentation do you maintain through SOP?

Where to go from here

Battery interviews reward depth + judgement. Don't memorise textbook answers — practise narrating real design trade-offs from your own projects. If you don't have project experience yet, build one (a Simulink pack model, a coin-cell aging study) and tell that story.

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