Tesla has asked owners to stop wrapping wet towels around handles to speed up the recharging process, warning that this can damage its Supercharger stalls.

Responding to a story posted by Inside EVs on X in May that claimed the trick worked, Tesla said placing a wet cloth over Supercharger recharging kit while juicing up "does not increase charging rates," and risks damaging cables because it fools temperature sensors into thinking the charger is cooler than it really is.

"Please refrain from doing this so our systems can run correctly, and true charging issues can be detected," Tesla's charging account said on X.

Kyle Conner, founder of EV media network Out of Spec Studios,
said in a recent podcast episode that, contrary to what Tesla was saying, the wet rag trick has been a reliable way to reduce charge times for more than seven years.

The method has to do with external temperature sensors on Tesla supercharging handles that are designed to decrease charging wattage to prevent people from burning their hands, which Conner said have never worked very well. By wrapping a wet towel around the charging handle, people not only avoided getting burned but also noticed a corresponding increase in charging amperage.

​​"Thermals on Tesla superchargers are terrible in the summertime," Conner said on the podcast episode.

That all changed around the beginning of June, when Conner suspected Tesla made changes to its charging logic to stop the wet rag trick from working.

"Tesla introduced some logic, I think rightly so, to try to stop the wet rag situation," Conner said of the update. After some recent testing of the method (which he reiterated several times during the discussion that Out of Spec doesn't endorse), Conner noted a wet rag on the handle still increased charging amperage and sped the process up, but with what seemed to be an artificial cap.

"Tesla must have logic to realize there's no feasible way the temperature sensor in the handle would cool off that quickly," Conner suspects. 

How about building chargers that don't overheat instead?

"I'm glad they put a stop to [the rag trick]," Conner opined during the podcast, but that doesn't mean he thinks Tesla is entirely in the right here. "They should come up with a connector that doesn't overheat," he added. 

Conner said that the wet rag trick, combined with the fact that Tesla chargers continue to have heating issues despite the addition of liquid-cooled cables in newer Superchargers, means Elon Musk's car company might have engineered itself into a corner.

Based on his reckoning, "Tesla doesn't know how to make, or at least is unwilling to install, a connector that can handle consistent high-current speeds," Conner said. Compared to other makes of public charging stations, "Superchargers seem to be the most temperature-sensitive of the bunch." 

We've asked the Out of Spec team for additional information.

Whether Tesla will be able to address its super-heated Supercharger issue could be further imperiled by the fact that Tesla reportedly laid off its entire Supercharger team in May, despite the company's charging port becoming the de facto US standard last year.

The decision to fire the entire Supercharger team in May was allegedly due to Musk's dissatisfaction with team leader Rebecca Tinucci, who told the billionaire she couldn't lay off additional team members without undermining Tesla's charging business. Responsibility for Tesla's charging network has since been given to the company's energy team responsible for selling Tesla's solar panels and Powerwall home energy storage products. 

So far it looks like the new Supercharger team has done less to roll out improved charging infrastructure, and is focused more on closing loopholes. We've asked Tesla to comment. ®

https://www.theregister.com//2024/07/29/tesla_harging_wet_rag/