NACS/J3400’s Support For 277V Charging Is A Huge Deal and Here’s Why

Most single household homes in America have 240V electrical energy readily available for charging, but unusually adequate most of our offices, hotels, schools, churches, and even bigger multi-tenant structures do not have 240V offered which's precisely why the SAE J3400 charging standard (NACS) supports 277V charging. By supporting 277V in addition to 240V (and 208V), the brand-new charge adapter will permit much faster charging at work and it'll make those workplace "chargers" cheaper and quicker to set up. It's a high voltage win-win-win with simply one small problem: No one but Tesla supports it at this time. Join me as I dive into J3400 and say why I believe 277V charging is more crucial than DC quickly charging.

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24 responses to “NACS/J3400’s Support For 277V Charging Is A Huge Deal and Here’s Why”

  1. @EVBuyersGuide Avatar

    You can bet that as soon as we can get our hands on a 277V NACS EVSE, we’re going to install one! My guess is that we might see one from Tesla soonish, but that’s just a guess…

    1. @olemissjim Avatar

      Tesla wall connectors ALREADY support 277v and I believe all Model3/Y and most s/x support 277

    2. @BrianCairns Avatar

      ​@@olemissjim277 volt support was always iffy on Tesla vehicles. The older wall connector supported it officially, but the on board charger has over voltage protection that trips just a bit higher than 277V, so it can be flaky if your voltage is even slightly high. As far as I know, the newer Tesla wall connectors don’t officially support 277V.

      Hopefully this changes with official support in NACS.

  2. @AdamJakowenko Avatar

    Love the use of a Mac SE/30 to demonstrate what uses a 120v plug 👍😆. I loved this video, thought it was really helpful as someone who understands EVs and the basics of charging but am by no means an electrician

    1. @EVBuyersGuide Avatar

      I should have used a shotgun mike to add in the floppy disk noises LOL

  3. @feiyulu Avatar

    Great information as always!

  4. @douglasmontgomery6315 Avatar

    Nice rundown..thanks

  5. @NickTimakondu Avatar

    Highlight of my day is Alex validating my nerd credentials by sticking with the video. Very informative and useful, thanks!

    1. @EVBuyersGuide Avatar

      Yay for power nerds!

  6. @laloajuria4678 Avatar

    this was excellent. great work. agree, hope it can help expand lvl 2 which is sorely needed literally everywhere!

  7. @ArtemDanilov Avatar


  8. @TheTravelingTank Avatar

    THIS is why I watch Alex on autos. No other car journalist would think about, let alone make a 14 minute video about a topic that (while somewhat niche for this platform) is such a big deal in the real world. Love the detail you go into as well

  9. @mattrigby9724 Avatar

    You remain the best at razor sharp accurate facts. Thank you for being such a power nerd.

  10. @_CarlosA Avatar

    This was great information! Great work!

  11. @MLHunt Avatar

    Very useful. I’ve been peripherally involved with electrical service in my work for years and this was a good explanation of how American electrical service works and the differences between residential and electrical service. I don’t think it was too deep into the weeds at all.

  12. @xchichard Avatar

    I rarely post comments, but I really wish you were my Circuits professor when I took that class all those years ago, Alex. This was great, thank you for this explanation.

  13. @AndrewMackoul Avatar

    Was not expecting an electrical engineering crash course in this video. Nice job!

  14. @FuncleChuck Avatar

    I really appreciate that final point about why a “Global” connector is not only never going to happen, it’s just a bad idea. We have totally different power systems in the US vs Europe, and what works best for the US would be awful in EU. A “universal” charging connector would be massive and wasteful.

  15. @HollowVortex81 Avatar

    Love the deep dive. Do more like this!!!

  16. @rik999 Avatar

    Excellent presentation, very educational and definitely not too deep. As someone who has cross shopped home and restaurant cooking appliances for my kitchen I’ve encountered the 208/240V conundrum. Glad to have the power differences explained so clearly.

  17. @geekdomo Avatar

    Thanks for covering this Alex, Power Geek here.

  18. @chrisdsouza8685 Avatar

    Extremely informative and helpful 👍

  19. @grandpabill7525 Avatar

    I now understand why 3 phase provides 208v instead of 240v. It’s been explained to me before but now I finally understand.

  20. @BrianCairns Avatar

    11:54 I suspect the other big hold up is the fact that NACS shares the same pins for AC and DC charging. This means that either the on board charger needs to tolerate 400 or 800 volts DC (as Tesla does), or you need additional contactors to disconnect the on board charger for fast charging.

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