Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

NEMA 1-15 120V charging without ground

This site may earn commission on affiliate links.
You cannot connect it to only the white wire! If you want this to work and be safe, it has to have the "Y"; TWO resistors of equal value, 60k is what I recommend, one going from AC Neutral to the EVSE ground pin, and one going from AC Hot to the EVSE ground pin. The balance is important and also insures the body of the car doesn't become a shock hazard.

You can also put two 1/4w resistors in series at half the value of ohms on each to end up with a 1/2w. Or put two 1/4w's in parallel at twice the value.

Tesla future newbie here, first post to the forum. Waiting on my M3 since September 2017, hopeful for Q1 2019 delivery. I know this is an old,old thread. I'm trying to get up to speed on a lot of things Tesla before it arrives, this is one of them. I have an ungrounded Winco 6KW tri-fuel generator with an L14-30 receptacle (240V 4-pin). I would like to have this generator as a backup for emergency charging. I -could- provide an actual earth ground with a copper grounding rod, but would prefer that the generator remain mobile. So, using this method, would I connect both hots to ground, as well as neutral to ground, using the 1/2W resistors? Is there any update to the resistor value 60K ohms? Does this solution still work with current Tesla charging systems?

BTW, I have a (Carol brand commercial) extension cord for this generator that shorts neutral to ground internally, and terminates in four 15-20 amp 120V outlets. It's clearly marked "For generator use only". It works (apparently normally) with power tools, refrigerators, and my house furnace fan using this generator.

Off topic, hoping the planned Supercharger in Kayenta, AZ gets installed this year for trips to Albuquerque, specifically for the 100 mile +/- leg Page AZ- Gallup NM.
 
You cannot connect it to only the white wire! If you want this to work and be safe, it has to have the "Y"; TWO resistors of equal value, 60k is what I recommend, one going from AC Neutral to the EVSE ground pin, and one going from AC Hot to the EVSE ground pin. The balance is important and also insures the body of the car doesn't become a shock hazard.

You can also put two 1/4w resistors in series at half the value of ohms on each to end up with a 1/2w. Or put two 1/4w's in parallel at twice the value.

Tesla future newbie here. Waiting on my M3 since September 2017, hopeful for Q1 2019. I know this is an old thread, I'm trying to get up to speed on a lot of things before it arrives, this is one of them. I have an ungrounded Winco 6KW tri-fuel generator with an L14-30 receptacle (240V 4-pin). I would like to use this generator as a backup for emergency charging. I -could- provide an actual earth ground with a copper grounding rod, but would prefer that the generator remain mobile. So, would I connect both hots to ground, as well as neutral to ground, using the 1/2W resistors? Is there any update to the resistor value 60K ohms? Does this solution still work with current generation Tesla charging systems?

BTW, I have a (commercial) extension cord for this generator that does short neutral to ground internally, and terminates in four 15-20 amp 120V outlets. It's clearly marked "For generator use only". It works (apparently normally) powering power tools, refrigerators, and my house furnace fan.

Off topic, hoping for a Supercharger in Kayenta, AZ for trips to Albuquerque, specifically the leg Page AZ- Gallup NM.
 
I'm not an expert here but until some experts help you here's my 2 cents.
Generators have square waves and sign waves. Those with square waves won't work with Tesla. Those with sign waves, some would work but some would not. Tesla UMC seems to have relatively smart safety software to detect any signs of failure or danger. For example if the output voltage fluctuates or getting lower as the load increase, UMC would stop charging.

I would say if you sort out your (unsupported) adapter, try it and if it didn't work, then it doesn't.
 
Thanks for the reply, hiroshly. Most generators rely on rotating magnets or rotating coils in a magnetic field, and are, by this design, inherently sine wave. Many less expensive inverters, on the other hand are modified sine wave, better described as modified square wave. I would not expect modified sine/square wave inverters to charge a Tesla. As I understand it, the issue is if the UMC will accept a 'spoofed' ground from an ungrounded generator, and designing the 'spoof' to be as safe as possible. There are a number of reports that a grounded generator or a bonded generator, Honda EB2000i, for example, (not EU2000i), will charge OK. Remember that I'm still waiting on my M3, hopeful for Q1 2019 delivery. I'll probably have to wait to sort all this out until I get it. Using an ICE generator is only going to be an emergency, power-outage backup, anyway. If I am able to use my 6KW Winco generator, which only puts out about 5.0KW sustained when running on natural gas, and derate that to 80%, that's 4.0KW going into the M3's battery, or on the order of 16 mph charge rate.
 
  • Like
Reactions: hiroshiy
I mean cut off 100 miles +/- from the leg Page - Gallup.
Welcome to the forum. We need more Tesla drivers in Utah. :)

I don't want to sound like a kill joy here, but not sure I would recommend going from Page directly to Gallop. When I looked at Google maps it showed 254 miles. Then I looked at Page to Flagstaff to Gallop and got 316. So you would travel 62 miles further and add 1 hour to your trip. Yea it is longer but not really that bad.

On the plus side you would have superchargers all the way and none of them very far apart. This would make the trip really easy to plan and lower your stress level with a new car.

Maybe next year Tesla will build a Supercharger in Kayenta. ( I really hope that they do as well )
 
>> Welcome to the forum. We need more Tesla drivers in Utah.

Thanks, KJD. My next door neighbor also has an M3 reservation, about 4 weeks ahead of mine. He might actually get his car this year & he travels frequently to Utah County and SLC. So do we, we also go to Logan. Hooray for SCs in Beaver and Nephi and family in northern Utah who have electric dryer outlets!

I hear you on Page to Gallup. The 'plan' says Kayenta Supercharger in 2018. I don't believe it. Flagstaff is very pretty, you've probably been there. If so, you know that it's very high elevation, lots of grades between Page & there. Another trip that has range difficulty is St. George to North Rim Grand Canyon & return. No Superchargers available for that route & little else, EVSE-wise. I found one RV park operator in Fredonia, AZ, Country Rose RV, that's not listed on any of the EV sites I've come across, and who says he'll be happy to sell time/KWH on a 50 amp hookup, although I don't think there's anything within walking distance of that RV to kill a couple hours while charging on a 14-50. He said no one has ever asked that before! Fredonia is about 75 miles one-way to the North Rim, again with some pretty substantial grades. I'm actually in Santa Clara, just west of St. George. My house to North Rim is about 305 miles R/T.

I see that you've been part of this users club since 2013. Do you come to St. George? The Supercharger here is lightly used and I've never seen it with fewer than 3 available chargers.

Apologies for getting far off the original topic.
 
Using an ICE generator is only going to be an emergency, power-outage backup, anyway.
I guess I'm going to be the person asking the obvious question. Your profile says you're in Santa Clara Utah. For this kind of really obscure and rare emergency backup situation where your house has no power...you are only about 4 miles from the St. George Supercharger. I would consider that my backup in case my house had no power. Why does that not seem sufficient?
 
  • Like
Reactions: davewill
I guess I'm going to be the person asking the obvious question. Your profile says you're in Santa Clara Utah. For this kind of really obscure and rare emergency backup situation where your house has no power...you are only about 4 miles from the St. George Supercharger. I would consider that my backup in case my house had no power. Why does that not seem sufficient?
Silly! The Supercharger probably won't be working if the zombie apocalypse comes.
 
Silly! The Supercharger probably won't be working if the zombie apocalypse comes.

Or maybe not working for lesser calamities, either. Yeah, the St. George supercharger is about 4 miles from my house. Current pricing is $0.22 / KWH for Model 3s at all SCs in Utah. My little hamlet of Santa Clara actually has its own generation plant, big Cat diesels powered by natural gas. A substantial earthquake could knock out the N.G. supply. I probably am getting ahead of myself in this, but I need something to give me my Tesla fix while I'm waiting for my M3.
 
Hi, I am traveling a little bit this weekend in Japan and will stay at a hotel with NEMA 1-15 2-prong outlet. This type of outlet is by far the most common here.

I guess Tesla doesn't offer NEMA 1-15 adapter for UMC. Will these alternatives work?

1) use UMC, NEMA 5-15 adapter and 3-prong-to-2-prong adapter (so ground pin open and not connected).
2) use Toyota prius PHV adapter, 3-prong-to-2-prong adapter and J1772 adapter. Prius adapter is known to work on priuses without ground connection......
.

Did anyone ever figure out an off-the-shelf solution for plugging in on a 1-15? I'm moving to Japan shortly and am contemplating taking my Model 3 with me, but it depends on whether I can charge comfortably. Any help is appreciated. Thanks!