Breaking EV Charging Bottleneck With Precision Cooling

Fast, DC charging can charge an electric vehicle battery from about 20 to 80 percent in 20 minutes. That's not bad, but it's still about six times longer than filling up a regular gasoline-powered car.

One of the main obstacles to even faster charging is cooling, especially uneven cooling inside large batteries for electric vehicles as the package charges. HydrohertzA British startup created by former motorsports and power electronics engineers says it has a solution: burning liquid coolant exactly where it's needed during charging. Its solution, announced in November, is a coolant-fueled rotary milling machine that delivers coolant exactly where temperatures spike, within milliseconds—much faster than any single-loop system can respond. In laboratory tests, this cooling technology allowed an EV battery to safely charge in less than half the time that was possible with traditional cooling architecture.

A Smarter Way to Move Coolant

Hydrohertz calls its solution Detravalve. It looks like a simple manifold, but contains two concentric cylinders and a stepper motor that directs coolant to four zones inside the battery. It is installed between the package cold plateswhich are designed to effectively remove heat from the battery cells through physical contact, and the main coolant supply circuit, replacing a tangle of valves, brackets, sensors and hoses.

To reduce costs, Hydrohertz has developed Dectravalve, which will be manufactured using off-the-shelf materials, seals and tolerances. Keeping it simple and relatively cheap could improve Dectravalve's chances of gaining popularity among automakers and suppliers known for their thriftiness. “Thermal management is trending toward simplicity and ultra-low cost,” says Chao-Yang WangProfessor of Mechanical and Chemical Engineering Penn State whose areas of research include addressing issues related to internal fluids 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, intelligent control is essential.

“If Dectravalve performs as advertised, I expect to see about a 20 percent increase in battery life, which is huge.”
—Anna Stephanopoulou, University of Michigan

Hydrohertz designed Dectravalve to work with regular water glycol, also known as antifreeze, making integration easy. Using a generic antifreeze avoids the testing step where the EV supplier or manufacturer would otherwise have to determine whether a specific formulation is compatible with other antifreezes. cooling system and does not cause unforeseen complications. And because a single Dectravalve can replace multiple valves and plumbing components in a traditional cooling system, it reduces parts count, reduces leak points and reduces warranty risk,” Hydrohertz founder and CTO. Martin Talbot claims. Tighter temperature control also allows automakers to downsize oversized pumps, hoses and heat exchangers, improving both cost and vehicle packaging.

The valve reads the block temperature several times per second and instantly switches the coolant flow. If a high load event (such as fast charging) is approaching, it is pre-positioned so that known hot spots receive more coolant before their temperatures rise.

Multi-zone control can also speed up warm-up to prevent battery degradation that occurs as a result of charging at low temperatures. “You can send warming fluid to quickly warm up half the package so it can safely begin to take the load,” says Anna Stefanopoulouprofessor of mechanical engineering University of Michigan who specializes in control systemsenergy and transport technologies. That half can begin to take the load while the system begins to more gradually heat the rest of the package, she explains. But the main function of Dectravalve remains to cool quickly heating problem elements so that they do not slow down charging.

Rapid response to changes in temperature inside the battery does not increase cooling capacity, but allows for much more efficient use of existing equipment. “Manage your coolant more precisely and you'll get more performance for free,” says Talbot.

Charging time can be reduced by 60 percent

At the beginning of 2025, Dectravalve underwent bench tests conducted by Warwick Production Team (WMG), a multidisciplinary research center at University of Warwickin Coventry, England, which works with transportation companies to improve the manufacturability of battery systems and other technologies. WMG compared Dectravalve's cooling efficiency with that of a conventional single-circuit cooling system using the same 100-kilowatt-hour battery pack. In 10 to 80 percent fast charging tests, Dectravalve kept peak cell temperature below 44.5°C and kept cell-to-cell temperature variation to just under 3°C without external intervention battery management system. Similar thermal performance for a single-circuit system is only possible by reducing the amount of energy the battery can accept—the same limitation that prevents fast charging from being on par with filling up with gasoline.

The key was to keep the cell temperature below 50 °C, since above this temperature lithium coating begins. A battery suffers permanent damage when lithium begins to coat the surface of the anode—the part of the battery where electrical charge is stored during charging—rather than filling the internal network of pores, as water does when it is absorbed by a sponge. The coating significantly reduces the battery capacity. Overheating the battery can also destroy the electrolyte. As a result, the flow of ions between the electrodes is inhibited. And reducing the flow inside the battery means reducing the flow in the external circuit that powers the car. motors.

Since Dectravalve maintained a low and uniform temperature and battery management system There was no need to play traffic cop and charge slowly to avoid overheating – charging time was reduced by about 60 percent. With Dectravalve, the battery reached 80 percent charge in 10 to 13 minutes, compared to 30 minutes with a single cooling circuit setup, according to Hydrohertz.

When batteries stay cool, they last longer

Using Warwick temperature data, Hydrohertz applied standard degradation models and found that cooler, more consistent packaging lasted longer. Stefanopoulou estimates that if Dectravalve works as advertised, it could increase battery life by about 20 percent. “It’s a lot,” she says.

However, it could be years before the system appears on new electric carsif ever. It will take years of cycle testing, crash testing and cost studies for automakers to approve a new coolant architecture. Hydrohertz reports that several electric vehicle manufacturers and battery suppliers have begun verification programs, and Talbot expects the number of licensing deals to increase as results become available. But even in the best case scenario, Dectravalve will not maintain its production model. batteries for electric vehicles cool at least three model years.