Breaking EV Charging Bottleneck With Precision Cooling

DC fast charging can charge an electric vehicle’s battery by about 20 to 80 percent in 20 minutes. That’s not bad, but it’s still about six times longer than filling the tank of a regular gasoline vehicle.

One of the main obstacles to even faster charging is cooling, particularly uneven cooling inside large electric vehicle batteries when they are charged. Hydrohertza British startup launched by former motorsport and power electronics engineers, claims to have a solution: torching coolant exactly where it’s needed during charging. Its solution, announced in November, is a rotating coolant router that sends coolant exactly where temperatures rise, and within milliseconds, far faster than any single-loop system can respond. In laboratory tests, this cooling technology allowed an electric vehicle battery to charge safely in less than half the time of conventional cooling architecture.

A smarter way to move coolant

Hydrohertz calls its solution Dectravalve. It looks like a simple manifold, but it contains two concentric cylinders and a stepper motor to direct coolant to four areas within the battery. It is installed between the cold plates of the packwhich are designed to effectively remove heat from the battery cells through physical contact, and from the main coolant supply loop, replacing a tangle of valves, brackets, sensors and pipes.

To keep costs low, Hydrohertz designed Dectravalve to be produced with commercially available materials, seals and tolerances. Keeping things simple and relatively cheap could improve Dectravalve’s chances of catching up with automakers and suppliers known for their frugality. “Thermal management tends towards simplicity and ultra-low cost,” says Chao-Yang Wangprofessor of mechanical and chemical engineering at State of Pennsylvania whose research areas include addressing internal fluid issues in batteries and fuel cells. Automakers would prefer passive cooling, he notes, but not if it slows down fast charging. So, at least for now, smart control is essential.

“If Dectravalve works as advertised, I would expect about a 20% improvement in battery life, which is a lot.”
–Anna Stefanopoulou, University of Michigan

Hydrohertz built Dectravalve to work with regular brine, also known as antifreeze, simplifying integration. Using a generic antifreeze avoids a step in the validation process where an EV supplier or manufacturer would otherwise have to determine whether a special formulation is compatible with the rest of the cooling system and does not cause unforeseen complications. And because a single Dectravalve can replace the multiple valves and plumbing assemblies of a conventional cooling system, it reduces the number of parts, reduces leak points and reduces warranty risks, says Hydrohertz founder and CTO Martyn Talbot. Tighter thermal control also allows automakers to reduce oversized pumps, pipes and heat exchangers, improving both costs and vehicle packaging.

The valve reads the pack temperature several times per second and instantly changes the coolant flow. If a high-load event, such as rapid charging, occurs, it prepositions itself so that more coolant is distributed to known hot spots before the temperature rises there.

Multi-zone control can also speed up preheating to prevent battery degradation from charging in freezing temperatures. “You can send a heating fluid to quickly heat up half the pack so it can start taking charge safely,” says Anna Stefanopoulou, a professor of mechanical engineering at the University of Michigan who specializes in control systems, energy and transportation technologies. This half can begin to accept the load, while the system begins to warm the rest of the bag more gradually, she explains. But Dectravalve’s primary function remains to cool the rapidly heating problem cells so they don’t slow down charging.

Rapid response to temperature changes inside the battery does not increase cooling capacity, but it leverages existing hardware much more efficiently. “Control the coolant more precisely and you get more performance for free,” says Talbot.

Charging times can be reduced by 60 percent

In early 2025, the Dectravalve underwent bench testing conducted by the Warwick Manufacturing Group (WMG), a multidisciplinary research center at the University of Warwick, Coventry, England, which works with transportation companies to improve the manufacturability of battery systems and other technologies. WMG compared Dectravalve’s cooling performance to that of a conventional single-loop cooling system using the same 100 kilowatt-hour battery. During fast charge tests from 10 to 80%, Dectravalve kept the maximum cell temperature below 44.5°C and kept cell-to-cell temperature variation just below 3°C without intervention from the battery management system. Similar thermal performance for the single-loop system was only made possible by reducing the amount of power the battery would accept – the very decrease that keeps fast charging from being on par with fill-ups of gas.

It was essential to keep the cell temperature below 50°C, because above this temperature lithium plating begins. The battery suffers irreversible damage when lithium begins to cover the surface of the anode (the part of the battery where electrical charge is stored during charging) instead of filling its internal network of pores like water does when absorbed by a sponge. Plating significantly decreases the charge storage capacity of the battery. Allowing the battery to get too hot can also cause electrolyte degradation. The result is an inhibited ion flow between the electrodes. And reduced flow into the battery means reduced flow into the external circuit, which powers the vehicle’s motors.

Because the Dectravalve maintained low, even temperatures (and the battery management system did not need to act as an energy traffic cop and slow down charging to avoid overheating), charging time was reduced by approximately 60%. With Dectravalve, the battery reached an 80% state of charge in 10 to 13 minutes, compared to 30 minutes with the single cooling loop configuration, according to Hydrohertz.

When batteries stay cool, they last longer

Using temperature data from Warwick, Hydrohertz applied standard degradation models and found that cooler, more uniform packs last longer. Stefanopoulou estimates that if Dectravalve works as advertised, it could increase battery life by around 20%. “It’s a lot,” she said.

Still, it could be years before the system appears on new electric vehicles, if ever. Automakers will need years of cycle testing, crash testing and cost studies before signing off on a new coolant architecture. Hydrohertz says several electric vehicle manufacturers and battery suppliers have launched validation programs, and Talbot expects licensing deals to accelerate as results come in. But even in the best-case scenario, Dectravalve won’t keep production EV batteries cool for at least three model years.