Heat is a significant obstacle in the swift charging process of almost any electric vehicle (EV). Car manufacturers have been exploring ways to maintain optimal charging temperatures, from employing liquid-cooled cables to elevating the voltage structure of vehicles. On the end-user front, certain individuals have discovered a method of accelerating charge rates by covering the charger handle with a damp cloth.
Instead of recreating existing methods or experimenting with unconventional towel techniques, General Motors is turning to a well-established approach to facilitate cooling. In a recent patent unveiled just last month, as spotted by Green Car Reports, GM outlines the utilization of nearly four-decade-old technologies to enhance the charging process of electric cars.
The “Cool Towel Trick”
Some Tesla owners have noticed that placing a cool and moist towel over the handle of certain Superchargers can elevate the charging speed during their Supercharging session. This represents a form of passive cooling, which aligns with GM’s objective through its new patent.
The key element lies in the dependable utilization of non-liquid cooling through a substance known as phase change material (PCM).
As the name suggests, this material transitions between phases as it absorbs and releases heat—moving from a solid to a liquid state—to cool the equipment it interacts with. In GM’s concept, this PCM encompasses the charging port and transforms from a solid to a liquid state as it absorbs heat.
The dissipation of heat then occurs through a heat spreader, akin to the cooling method employed in numerous electronic devices over decades. This passive cooling system is acknowledged for its efficiency and reliability, and additionally aids in weight reduction compared to more intricate solutions.
So, why is this groundbreaking? Similar to other concerns prevalent in the EV sector, the crux of the matter boils down to a singular element: charging duration.
Should the charging components of an EV become excessively hot, the vehicle and charger enter negotiations to reduce the charge rate in order to safeguard the components. This is where the “towel trick” comes into play—it assists in cooling the various components and sensors that manage the charge rate adjustment. Rather than solely relying on my explanation, here’s how GM articulates it in its patent:
If the charge port temperatures surpass a predetermined threshold, the onboard control module or charging station might diminish the charging rate. This could result in continued charging at a reduced rate or a temporary pause to allow the charge port temperatures to decrease. Upon dropping below the preset threshold, the charge rate may elevate once more and/or the charging process could recommence. Curtailing the charge rate due to elevated charge temperatures could prove inconvenient for the user. Consequently, the industry would embrace a charge port cooling mechanism not reliant on liquid cooling approaches.
Various alternatives exist for cooling charging components. For instance, Tesla integrates liquid-cooled charging cables in V3 Superchargers for this purpose. Meanwhile, Hyundai, Porsche, and other automakers have transitioned to 800-volt battery architecture, permitting reduced current flow during charging and subsequently minimizing heat generation. Nonetheless, if proven beneficial in the automotive sector, the employment of PCM appears to be a cost-effective and straightforward move.
There remains uncertainty regarding whether GM will incorporate this technology into its upcoming vehicles, particularly amidst its shift towards Tesla’s NACS standard. At times, automakers register somewhat unconventional patents, hence the technology’s integration into a production vehicle remains undetermined.