20 EV Charging Engineer Interview Questions

Charging engineer interviews split between hardware (designing the charger), firmware (running OCPP / ISO 15118), site engineering (deploying it) and operations (keeping it alive). Here are 20 questions across the four tracks.

Hardware (6)

• Compare PFC topologies for an AC charger.
• Walk through an LLC resonant converter for a DC charger.
• How do you size DC-link capacitance for a 60-kW fast charger?
• What's the CT and PT placement strategy in a charger?
• Explain EMI filter design for a fast charger.
• What's residual-current monitoring and why is it mandatory?

Firmware + protocols (8)

• Walk through the OCPP boot-notification sequence.
• What's the difference between OCPP 1.6 and 2.0.1?
• How does ISO 15118 plug-and-charge authenticate?
• Explain the CCS-2 charging session state machine.
• What's the role of a PKI in plug-and-charge?
• How do you implement OTA on a charger that's deployed in the field?
• Walk through the SECC + EVCC interaction.
• What happens when network connectivity drops mid-session?

Site engineering + operations (6)

• Walk through your site-survey checklist for a 30-kW DC charger installation.
• What's your typical earthing layout?
• How do you coordinate with DISCOM for a high-load site?
• What's your standard commissioning report?
• How do you triage an uptime issue from the NOC?
• What KPIs do you report to the operator on a monthly basis?

Where to go from here

Charging interviews vary heavily by company type. At hardware OEMs (Delta, Servotech) the focus is power-electronics depth. At operators (Tata Power EZ Charge, Statiq) it's deployment + uptime. Prep the area that matches your target company's product.

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