As smartphone and laptop use accelerates worldwide, the question of what happens to retired batteries sparked an innovative solution by Prodip Chatterjee, co-founder of the sustainable startup Nunam. Supported by the Audi Environmental Foundation, the startup has taken on the challenge of providing renewable energy storage systems in India by upcycling old lithium-ion batteries.
Chatterjee, a German citizen of Indian heritage, was struck by the idea during his visits to India, where frequent power outages plague rural areas. “I’m disappointed every time to see that the poor living conditions hardly change,” he explained. Recognizing how critical electricity is for improving quality of life, he turned his concern into action.
Initially experimenting with old phone batteries, Chatterjee teamed up with co-founder Darshan Virupaksha in 2017 to create mobile energy storage systems from retired laptop batteries. These systems have since been developed to power vegetable vendors’ stalls after dark and provide essential energy for phones, fans, and lamps in homes.
The process begins by sourcing used batteries from local scrap dealers in Bengaluru and other Indian cities. Chatterjee’s team tests the salvaged cells, only using those with at least two-thirds of their original capacity to create durable renewable energy units. “It’s crazy to think about how much potential just lands in the trash,” he remarked. Each storage unit is larger than a typical power bank, containing up to 120 battery cells to meet the needs of small businesses and homes.
To ensure sustainability, Nunam developed an app and tracking system that assigns a QR code to each battery cell. This system monitors usage data, predicting when batteries need replacement and preventing them from being discarded irresponsibly. The team is also exploring a rental model to further promote a circular economy.
While the pilot phase focuses on producing 25 prototypes to distribute in rural areas, Chatterjee emphasizes the importance of trust and affordability in their mission. “It’s important to us that we can sell the renewable energy storage unit as inexpensively as possible so that even the poorest customers can have access to a bit of electricity,” he shared. The goal is not only to provide power but to inspire others worldwide to innovate in sustainable energy reuse.
With co-founder Virupaksha managing operations in India and Chatterjee handling business from Germany, Nunam continues to push forward, proving that discarded batteries can bring new life to underserved communities. Their vision of a brighter, sustainable future is already lighting the way for vegetable vendors and rural families alike.
The energy is there, Nunam says — we just need to use it.
