TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker and becoming a Supporting Member. For more info: Support TMC

Building a 220 volt charger

Discussion in 'Model 3: Battery & Charging' started by Heynow999, Jun 17, 2018.

  1. Heynow999

    Heynow999 Member

    Nov 4, 2013
    Toronto, Canada

    I have a model 3 and I have been given permission to charge at work. Where I park there are plugs in front of most parking spaces for block heaters. They are 20 amp, 110 volt GFCI plugs. There are 4 receptacles on each of these towers. I took a meter and measured the voltage between the hots on either side of the tower and sure enough I get 208 volts. Its probably 3 phase power at the building.

    So what I want to do is make my own version of a "Quick 220" adapter. I would use two 20 amp cords run into an outdoor box with a stove plug on it I could run one of the hots to one side of the stove plug, the other hot to the other side of the stove plug, crank the charge rate on the car down to 16 amps and away we go.

    So my questions are, is the 208v a problem? Do I need the neutral to make it work? I know when I installed my HPWC the neutral is not used. Can I adjust the amps down that low? Will this work with two GFCI? (I think im ok with that because I am charging right now on that plug at 110v. 24+ hours to go for a full charge!)

    Attached Files:

  2. yuhong

    yuhong Member

    Mar 11, 2018
    Burnaby, BC
    208V should be no problem for a Quick220 or the car. No neutral would also not be a problem.
  3. eprosenx

    eprosenx Active Member

    May 30, 2018
    Beaverton, OR
    Lots of comments:

    1. Building your own box / adapter could be dangerous since once you plug in one 120v plug plus a 240v load, you may have energized the "hot" pin on the second 120v plug that is not hooked up yet. Also, in scenarios where one breaker blows you may be backfeeding voltage into that wire such that someone troubleshooting the circuit might not expect it.
    2. If you do this, I would probably recommend building it with a NEMA 6-20 receptacle and get the Tesla 6-20 adapter (assuming you have a UMC gen 2).
    3. I think if the plugs are GFCI then you are SOL. Each circuit is expecting current of exactly equal amounts on the hot vs. the neutral. You are going to be redirecting that flow to not use the neutral at all, so the GFCI will blow.
    4. 208v is no problem whatsoever. Any EV will be fine with that. Having roughly 73% faster charger than 120v would be nice!

    Perhaps you could figure out how the power architecture for these plugs is setup and convince your employer to reconfigure it slightly to allow what you need? Best case maybe there is a circuit breaker panel in the lot somewhere where a 240v plug could be added? Or a couple of 20a circuits could be switched over to give you a single 208v circuit pretty easily.
    • Helpful x 1
    • Informative x 1
  4. ewoodrick

    ewoodrick Well-Known Member

    Apr 13, 2018
    Buford, GA
    There are some cables being made to do this, but I'd really recommend getting an electrician to verify the circuits first.
    Frying the car is bad, burning down your house is teriible

    Burning down a business can really suck.
  5. Rocky_H

    Rocky_H Well-Known Member

    Feb 19, 2015
    Boise, ID
    Dang, @eprosenx is hitting all the good stuff. I had a couple of those things I was going to mention--it's dangerous/unsafe to build one yourself, and it just can't work on GFCI circuits anyway, which all outdoor 120V outlets are required to be.
  6. davewill

    davewill Active Member

    Feb 5, 2014
    San Diego, CA, US
    #6 davewill, Jun 18, 2018
    Last edited: Jun 18, 2018

Share This Page

  • About Us

    Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.
  • Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.