A modern electric vehicle (EV) is about a lot of advanced hardware and software engineering. Lots of water may be used to clean it, but not as a tech differentiator. For Exponent Energy, a Bengaluru-based technology startup, water is the differentiating factor for its core pitch of an industry-leading 0-100% battery charge in 15 minutes, for all types of EVs, as it claims.
The 3-year old startup, also backed by Pawan Munjal, and the Motherson Group, has two main objectives to build its business on – charging an EV as quickly as possible, and a battery that costs as little as possible. “For this, we had to rethink the stack. The first stack was how do I take a regular lithium ion cell and charge it up? There a lot of things are on BMS and our charging algorithms. And as we achieved success in that, we ended up in the second problem, the generated heat,” Exponent Energy’s Founder and CEO Arun Vinayak recounted the tech development process.
According to the engineer-CEO, a 15-minute fast charging generates 256 times more heat than the industry average of a 4-hour charging cycle. Unless extracted, overheating will stall the charging. The ideal thermal range or a ‘sweet spot’ is 25-35°C. With liquid cooling, Vinayak said, the best that can be achieved is 50°C.
A HVAC (Heating, Ventilation, Air-Conditioning) system holds the solution. However, it’s an expensive proposition, especially for three-wheelers. May not for a Tesla. It has an on-board HVAC system costing an estimated INR 2 lakh, for the thermal control of the battery pack. An HVAC system for an electric two-wheeler is estimated to cost around INR 1 lakh. That’s more than the price of some models available today.
The secret sauce
And, that’s what triggered the idea of making the HVAC system a part of an Exponent’s charging station. The 600 amps charger also pumps out refrigerated water (10°C) to prevent the battery pack from going bonkers. Every charging station has capacity to store 30 litres of water, which get recycled. Exponent Energy has obtained a patent for this technology, in India, and some overseas markets.
The BMS (Battery Management System) has to be robust too to ensure efficient charging with minimal degradation to the cells. An improper BMS can lead to Li-ion crowding around the battery’s anode, leading to what is called ‘lithium plating’, resulting in significant cell degradation.
Each charging station or ‘e-pump’ has 6kW of cooling power. With this technology approach, Exponent Energy claims that electric 3-wheelers with its tech can do the same duty cycles as other electric cargo carriers of equivalent size, with a 30% smaller battery pack. It claims the three-wheeler can be more affordable by around 30% too.
The condition however is that the 3-wheeler has to be equipped with Exponent Energy’s battery pack and connector. It has to be charged in an Exponent station. These 3-wheelers can also be fast charged in a DC charger in an hour, or slow charged in a home AC charger.
With the conditions of using its battery pack, connector, and charging station to address a major issue of range anxiety for EVs, one may see Exponent Energy’s approach as exclusive, and therefore non-democratic. “We are not trying to democratise technology. We are trying to democratise EVs. We are trying to democratise energy for EVs and make them more affordable,” Vinayak said.
Consistent fast charging is not recommended for EV battery packs, to maintain their health. Adding another technology bet, Exponent Energy offers a warranty of 3,000 charging cycles for its battery pack. It says this approach has been validated by TUV India, an independent testing laboratory of TUV Nord Group, Germany.
According to the startup, TUV found 13% degradation after 3000 charging cycles of 15-minute rapid charging. And that is ‘3-4x’ better than the industry average, Vinayak said during a presentation. The Exponent battery pack consists of LFP cells.
Expansion plans
Currently, Exponent Energy has 30 charging stations across Bengaluru, 20 of which are run by franchisees. Each of them costs INR 5 lakh. With the 15-minute fast charging tech, the business case gets better. “You need roughly 15 charges a day. 10 is a borderline case. If you’re below 10 charges a day in any station around the world, you’re not going to be profitable,” Vinayak said.
But, for Exponent Energy to get the critical volumes, it needs more OEMs to adopt its technology stack. Currently, electric 3-wheeler maker Altigreen is the only one. Vinayak is hopeful of getting a few more, including a bus maker, as partners within the next 6 months. By the end of FY24, Exponent Energy plans to be present in 5 more cities – Delhi NCR, Mumbai, Hyderabad, Chennai, and Ahmedabad.
With these plans, the startup expects to breakeven in a “couple of years”. For funds, it has raised USD 18 million so far, which Vinayak says puts Exponent Energy in a comfortable position for now.
Will Exponent Energy’s tech be a game changer in the emerging Indian EV industry? The answer will be clear within a year or so, but it does stand as a disruptive idea that could fuel the collaboration trend further in the automotive industry.
Also, in this disruptive age, could it be that someone else is working on an even faster charging tech?
