Exponent: Solving a two-sided problem of fast charging

With an off-board cooling system, this venture has found a way to charge batteries fast without degrading their viability

By Harichandan Arakali Forbes India Staff

Published: Sep 15, 2023 06:10:31 PM IST

Updated: Sep 18, 2023 03:43:56 PM IST

Full Bio

Sanjay Byalal Jagannath (right) and Arun Vinayak, Cofounders, Exponent Energy Image: Nishant Ratnakar for Forbes India

Arun Vinayak, founder of Exponent Energy, explains charging of electric vehicle (EV) batteries as a two-sided problem. In the fossil fuel world, petrol or diesel just sits in a dumb tank and energy is delivered by burning the fuel in an engine. Therefore, energy companies built the delivery network, and the auto companies built the engines and the powertrains.

In the EV world, energy transfer from the grid to the EV, and the storage and delivery are complex processes. One has to worry about cell chemistries and thermal management, among other things. “By definition, it’s a two-sided problem,” he says.

Vinayak, former chief product officer at Ather Energy, and his friend Sanjay Byalal Jagannath, previously a supply chain specialist at HUL, started Exponent in 2020 to tackle this problem.

Vinayak says batteries don’t get damaged while discharging, meaning when one is driving an EV around. It’s really when it’s being charged that the batteries—comprising their constituent cells and all the electronics that go into managing them—are under most stress.

Also read: Log9: Holding the key to India's self-reliance in critical areas of the EV sector

And a critical aspect is keeping the lithium ion batteries in the 25 to 35 degree Celsius range that they like. Exponent has innovated a charging station plus battery combination that moves the problem of cooling to the pump.

They’ve built a way to pump cold water under pressure into the battery pack while charging to keep them cool. And when the charging is done, they have a way to suck out all the water and the EV is good to go.

All this involves an off-board HVAC (heating, ventilation, air conditioning) system along with a pressure system, a pump, that actually sits inside the e-pump, Exponent’s charger. And much work has gone into the connector, Vinayak says. It has signal pins, power pins, and fluid couplers that make a seal or break it based on what’s happening.

“For the driver, it’s a simple experience. Just plug in the connector, just one click, and all these pins sort of engage,” he says. And there’s a lock that won’t allow the connector to be pulled out mid-charging. Once they lock engages, the system builds up pressure, pumps in the cold water and once the battery achieves the right temperature, the system also starts pumping in current.

Exponent promises zero to 100 percent charge in 15 minutes and still guarantees the batteries will be good for at least 3,000 charging cycles.