• Extension cables for Superchargers disrupt built-in safety mechanisms, increasing the risk of overheating.
  • Using third-party cables could cause electrical shorts, making them a serious safety hazard.
  • Future Superchargers will feature longer cables designed to support non-standard charging ports safely.

Tesla recently opened its Supercharger network to other brands. Some cars that can use the chargers have charging ports that don’t allow for sitting in one parking spot. As a result, third-party vendors have created extension cables. Now, a Tesla engineer says they’re a bad idea and he broke down the potential safety risks.

Most Tesla vehicles have their charging port positioned in a way that allows for easy charging when parked at a Supercharger. That’s not always the case with EVs from other brands. Several third-party companies including A2Z EV have developed extension cords for this purpose, but according to the lead engineer of the Cybertruck, these cords pose a risk.

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Tesla’s Wes Morill responded to a thread on X touting one of these NACS DC cords, warning about heat. “Would recommend AGAINST using an extension cord on a supercharger (or any DC charging station with a liquid cooled cable). Have seen multiple instances of the cable overheated and shorting DC +/-” he says.

According to him, the handle of the charging cable is constantly monitoring temperature and the Supercharger reacts to that reading. Adding an extension cable changes that equation and according to Wes, “that safety goes away.” Understandably, nobody wants their EV or even their EV cord to burn up so this advice seems altruistic.

Notably, he also let slip that Tesla understands this issue and is working on a fix with fourth-generation Superchargers. Those stations will evidently have longer cables to accommodate vehicles that aren’t made by Tesla. Interestingly, Morrill said too that he would willingly discuss the technology with A2Z EV privately.

For now, let it be a warning to anyone willing to try an extension cord. Shorts and fires aren’t totally unheard of in that realm and certainly don’t seem worth the risk.