How they make the world's fastest EV chargers | Exponent Energy CEO gives factory tour! BP2B S2 Ep.7
Arun Vinayak (guest)
In this episode of Best Place To Build, featuring Arun Vinayak, How they make the world's fastest EV chargers | Exponent Energy CEO gives factory tour! BP2B S2 Ep.7 explores exponent Energy’s full-stack approach to ultra-fast EV charging in India Exponent Energy targets India’s commercial vehicles, arguing that although they are only ~10% of vehicles, they consume ~70% of on-road energy, making them the highest-leverage segment to electrify.
Exponent Energy’s full-stack approach to ultra-fast EV charging in India
Exponent Energy targets India’s commercial vehicles, arguing that although they are only ~10% of vehicles, they consume ~70% of on-road energy, making them the highest-leverage segment to electrify.
The company claims “world’s fastest” 15-minute full charging from 3-wheelers up to buses, including a 1.5 MW charger built in India, to eliminate downtime and improve charging-station throughput economics.
Arun explains why fast charging is a battery-chemistry and control problem (lithium crowding/plating, cell-to-cell variation) that cannot be solved by simply pushing more current, requiring closed-loop, cell-aware charging instead of open-loop CCCV.
Exponent’s technical differentiators include real-time sensing and control, cloud “digital twins” per cell, and moving expensive HVAC/cooling off the vehicle and into the charger via a connector that carries power, data, and coolant.
The episode weaves Arun’s builder origin story (scrap-built car at 16, IIT Madras/C FI/Raftaar, Ather CPO) with Exponent’s “engineering + economics” philosophy, current scale (150 chargers, 2,000+ pilot vehicles), and the challenges of building deep tech in India.
Key Takeaways
Fast charging is fundamentally a two-sided “transaction” problem, not a charger-only upgrade.
Exponent argues that unlike petroleum (easy transaction, hard upstream), EVs have energy everywhere but a hard midstream transaction; rapid charging requires charger, battery pack, BMS algorithms, connector, and station to be designed as one system.
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Open-loop CCCV charging is “probabilistic”; rapid charging needs deterministic, cell-aware control.
CCCV applies generic current/voltage profiles despite cell aging and pack differences; Exponent claims it senses cell behavior in real time, predicts crowding, dynamically adjusts (and can reverse) current per cell, and learns via cloud models.
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Lithium plating is the degradation cliff that fast charging must avoid.
Arun describes lithium ions “traffic-jamming” at the anode during aggressive charging, triggering irreversible plating that removes active material and causes the familiar “knee” in degradation curves.
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Thermals are necessary—but secondary to electrochemical control.
Even perfect cooling cannot prevent plating if charging is uncontrolled; however, once charging goes faster, heat scales sharply (I²R), so robust thermal systems are required for field reliability.
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India’s commercial EVs can’t afford vehicle-integrated HVAC; move cooling to the charger.
Because many commercial vehicles in India heat up mainly during charging (low-speed duty cycles), Exponent relocates heating/cooling hardware to the charging station and pumps coolant into the battery through the connector, lowering vehicle cost and complexity.
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15-minute charging improves not only driver time but charging-station business viability.
High utilization is critical because urban real estate is expensive; faster sessions increase kWh sold per square foot, reduce queues, and make infrastructure investable without overcharging price-sensitive commercial operators.
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Manufacturing precision and uniformity become a ‘tolerance game’ at rapid-charge extremes.
To keep all cells within narrow thermal/electrical bands, Exponent highlights automated welding, adhesive-based assembly (“sticking” vs bolting), uniform cold-plate contact, and extensive durability testing (3,000+ cycles) to validate life claims.
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Notable Quotes
“Commercial vehicles are just 10% of the vehicles on the ground, but they consume 70% of the energy.”
— Arun Vinayak
“One-hour charging… is not fast enough. Imagine going to a public spot and waiting one hour, twice a day.”
— Arun Vinayak
“If you just amp it up blindly, you will destroy the cell.”
— Arun Vinayak
“We’re going from this to a deterministic method, where we real-time understand what’s happening with every cell.”
— Arun Vinayak
“Engineering without economics is just a science project.”
— Arun Vinayak
Questions Answered in This Episode
On the 1.5 MW bus charger: what grid connection, transformer, and demand-management setup is required at a typical site in India?
Exponent Energy targets India’s commercial vehicles, arguing that although they are only ~10% of vehicles, they consume ~70% of on-road energy, making them the highest-leverage segment to electrify.
Get the full analysis with uListen AI
Your closed-loop system adjusts current per cell—what sensors and sampling rates enable that, and what parts run on-pack vs on-charger vs in the cloud?
The company claims “world’s fastest” 15-minute full charging from 3-wheelers up to buses, including a 1. ...
Get the full analysis with uListen AI
How do you validate that 15-minute charging doesn’t accelerate degradation under real operator behavior (partial charges, high ambient heat, repeated top-ups)?
Arun explains why fast charging is a battery-chemistry and control problem (lithium crowding/plating, cell-to-cell variation) that cannot be solved by simply pushing more current, requiring closed-loop, cell-aware charging instead of open-loop CCCV.
Get the full analysis with uListen AI
Moving HVAC to the charger is clever—what are the reliability and maintenance implications of fluid coupling in dusty, high-usage commercial stations?
Exponent’s technical differentiators include real-time sensing and control, cloud “digital twins” per cell, and moving expensive HVAC/cooling off the vehicle and into the charger via a connector that carries power, data, and coolant.
Get the full analysis with uListen AI
You mentioned the industry’s CCCV approach is probabilistic—what failure modes have you observed in the field that directly motivated your ‘deterministic’ controls?
The episode weaves Arun’s builder origin story (scrap-built car at 16, IIT Madras/C FI/Raftaar, Ather CPO) with Exponent’s “engineering + economics” philosophy, current scale (150 chargers, 2,000+ pilot vehicles), and the challenges of building deep tech in India.
Get the full analysis with uListen AI
Transcript Preview
Exponent is actually in this cusp of energy, automotive, [chuckles] and, and financing, which is very important for commercial vehicles. So we are in three big boy segments.
Building in India, Make in India-
Yeah
... is hard the first time.
Yeah.
And you've chosen to do this twice.
Yeah, sometimes I, I ask myself why. [laughing] But those times are maybe 5% of the times. 95% of the time, I'm happy. It, it makes no sense to just... At least personally, it, it, it's not exciting to build lab prototypes, right? If you have to actually meaningfully change the world, you have to build crazy tech that actually disrupts. Energy is all about battery technology and charging network, so we are a full-stack energy company. Uh, are we a battery company or are we a charging company? [upbeat music]
Hello, and welcome to the Best Place to Build Podcast. Today, we are at the Exponent Energy factory in Bangalore. Uh, we are with Arun Vinayak. He's the CEO and co-founder of Exponent, also IIT Madras alumnus, batch of 2013. Uh, he was the CPO, chief product officer, for Ather for five, six, seven years. Uh, hello, and welcome to the podcast, Arun.
Hey, Amit, thanks so much for having me here. Super! Thanks for, thanks for coming to the factory.
Yeah. Um, this is amazing. Thank you so much. Um, I want to start by asking you, what does Exponent do?
Exponent is fundamentally an energy company. Uh, what you think of energy today as oil, tomorrow is batteries plus chargers. So we are building the full-stack energy company, uh, which includes battery technology and charging ecosystem that will power the future of energy, which, and power all the electric vehicles in the future.
Right. And you're focused on the commercial vehicle segment?
Yeah, we're exclusively focused on commercial vehicle seg- segment. Um, in India, commercial vehicles are just 10% of the vehicles on the ground, but they consume 70% of the energy. So-
Right
... uh, that's the biggest energy segment for us to electrify. And, uh, they, they all need ultra-fast... They all need the freedom, flexibility to keep earning, so we built the world's fastest charging tech for them, 15 minutes fast charging.
And this 15 minutes is for, uh, three-wheelers?
Three-wheelers to buses, so even buses-
Three--
... charging 15 minutes.
Okay.
So we have, like, a one-and-a-half megawatt charger that charges these buses up in 15 minutes.
Okay.
Uh, it's the world's highest power charger.
You can charge a bus in 15 minutes?
Yeah, we, we already charge a bus in 15 minutes.
It takes longer to fill fuel in a bus.
Yeah. I, I-- actually, you're right. I think bus, bus refueling time is longer than 15.
Nice. Very interesting. And we are here, sitting here, right here, so we have this in the background. What is this?
So this is actually our ePump. Uh, so, like you have a fuel pump today, the-- this will be ePumps, where you can come and recharge like you refuel. Uh, this is actually our intra-city ePump that caters to three-wheelers and LCVs, and the smaller form factors. Uh, that's the connector right there. So you, you go, you connect, and you charge. And, uh, uh, this one as well.
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