Ather Grid Battery Engineer Interview: Rounds, Questions and Preparation

What the job involves

A Battery Engineer in the EV and cleantech sector designs, tests, and optimises battery packs for electric vehicles, focusing on cells, battery management systems (BMS), thermal management, and safety. Day to day, they work with cross-functional teams to select cells, run simulations and tests, analyse data, and ensure packs meet performance, cost, and safety targets. At companies like Ather Grid, they also support integration with charging infrastructure and field diagnostics.

Role and Technical Knowledge

1. 1

   Explain the difference between Li-ion cell chemistries like NMC, LFP, and LTO. Which would you choose for a two-wheeler EV and why?

   Compare energy density, cycle life, safety, and cost. For two-wheelers, NMC is common for high energy density, but LFP is gaining for safety and longevity. Mention trade-offs.

2. 2

   What are the key functions of a Battery Management System (BMS) in an EV?

   Cover cell monitoring, SoC/SoH estimation, cell balancing, thermal management, protection (overcharge, overdischarge, overcurrent), and communication with the vehicle controller.

3. 3

   How would you design a thermal management system for a battery pack used in Indian summer conditions?

   Discuss passive vs active cooling, air vs liquid cooling, phase change materials, and the importance of uniform temperature distribution. Mention ambient temperatures up to 45-50°C.

4. 4

   What is the difference between SoC and SoH? How can each be estimated?

   SoC is remaining charge, SoH is degradation over time. Methods: voltage-based, Coulomb counting, impedance-based, model-based (Kalman filter), and data-driven approaches.

Practical Scenarios and Problem Solving

1. 5

   A battery pack in the field is showing reduced range after 6 months. How would you diagnose the issue?

   Outline a systematic approach: check SoH data, cell balancing, temperature logs, charging patterns, and possible cell degradation. Suggest capacity testing and cell replacement if needed.

2. 6

   You need to select cells for a new pack. What parameters would you consider and how would you test them?

   Consider capacity, internal resistance, voltage, cycle life, temperature performance, and safety. Testing includes capacity check, pulse tests, and accelerated aging.

3. 7

   How would you ensure the battery pack meets safety standards like AIS 156 for Indian EVs?

   Mention design features like fuse, venting, thermal runaway propagation prevention, and testing for vibration, shock, thermal shock, and overcharge. Reference AIS 156 requirements.

4. 8

   Describe a time you solved a technical problem with limited resources. How did you approach it?

   Use STAR method: Situation, Task, Action, Result. Highlight creativity, prioritisation, and learning from constraints.

Behavioural and Teamwork

1. 9

   Tell me about a project where you worked in a team. What was your role and how did you handle disagreements?

   Show collaboration, communication, and conflict resolution. Emphasise listening and finding data-driven solutions.

2. 10

   Describe a situation where you had to learn a new technology quickly for a project.

   Highlight self-learning, resourcefulness, and application of new knowledge. Mention specific tools or concepts learned.

3. 11

   How do you prioritise tasks when working on multiple deadlines?

   Discuss methods like Eisenhower matrix, communication with stakeholders, and focusing on impact. Give an example from academics or internships.

HR and Company Fit

1. 12

   Why do you want to work in the EV battery domain, and why our company?

   Show passion for clean energy and sustainability. Research the company's products, mission, and recent developments. Align your goals with theirs.

2. 13

   Where do you see yourself in 3-5 years in this role?

   Express interest in growing into a technical expert or team lead, contributing to advanced battery technologies. Show commitment to the sector.

3. 14

   Are you willing to relocate or work in a manufacturing/R&D facility if required?

   Be honest but flexible. Mention willingness to adapt to business needs and eagerness to gain hands-on experience.

4. 15

   What are your salary expectations?

   Research industry standards for freshers in EV battery roles. Provide a reasonable range and express flexibility based on overall compensation and growth opportunities.