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120v Extension Cord Charging

EmilyLC

Member
Dec 7, 2020
8
4
Vancouver
Hi everyone! People were super helpful on my first general-tips post, so I thought I'd shoot out another with a more specific question. I've looked through the existing threads and haven't found all that much that's applicable to my situation.

General question: Is charging from a 120v (regular house plug) with a 50' extension cord problematic?

Specifics: I live in a shared house and the (open-air) parking spot in the back lane is far from the nearest plug. I am only here for another 7 months or so, so I have no plans to install a wall-charger. I think the spot is about 50' from the regular 120v outlet on the wall at the outside of the house (there is not an additional dryer charger). I've found a 10-gauge, 15 amp cord that looks (and is priced) quality and will cover the distance - see the amazon link. I live in Vancouver, so there are some super-chargers at a bit of a distance, and there are half a dozen relative-convenient non-Tesla chargers a 10 minute driver away. Charging at home isn't necessary, but it would be very convenient and give me peace of mind.

https://www.amazon.ca/gp/product/B0163AKLK4/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Let me know what you think! I noticed one thread about 120v causing a short circuit? I have zero understanding of either physics or electrics so I just want to know if this plan carries any risks. thanks!!
 
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RayK

Active Member
Apr 5, 2016
1,881
1,832
San Jose, CA
Note that if you do 120V/15A charging via a 50 foot extension cord, your charging rate will be about 3 miles per hour, possibly less given your location in a cold climate.

There should be no risk of a "short circuit" as long as your extension cord is of good quality and that you make sure that the outlet and mobile connector remains out of water/rain/snow.

If you can't get to a Supercharger, use of a J1772 adapter on Level 2 30A charging station will yield about 23-25 miles per hour, so if you can plug in your car while at work, that will go a long way of alleviating your concerns of "low range".

Edit: I should also note that if spending about CAD$600 for a CHAdeMO adapter isn't too much for you, that you consider this as an alternate means of charging your car. I looked at the plugshare.com site and there are many CHAdeMO stations in the Vancouver area; about double the number of Tesla Superchargers. A quick check shows at least several sites with BC Hydro fast chargers are currently free, otherwise the going rate is about $0.35/kWh. Yes, it might take 10,000 miles of driving (~25 full charges at zero cost) with the CHAdeMO adapter for it to return your initial investment but it's one more way of getting juice into the car. If you are planning to take some long distance trips across Canada, the CHAdeMO adapter will be useful to have.
 
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nwdiver

Well-Known Member
Feb 17, 2013
7,786
10,027
United States
Hi everyone! People were super helpful on my first general-tips post, so I thought I'd shoot out another with a more specific question. I've looked through the existing threads and haven't found all that much that's applicable to my situation.

General question: Is charging from a 120v (regular house plug) with a 50' extension cord problematic?

Specifics: I live in a shared house and the (open-air) parking spot in the back lane is far from the nearest plug. I am only here for another 7 months or so, so I have no plans to install a wall-charger. I think the spot is about 50' from the regular 120v outlet on the wall at the outside of the house (there is not an additional dryer charger). I've found a 10-gauge, 15 amp cord that looks (and is priced) quality and will cover the distance - see the amazon link. I live in Vancouver, so there are some super-chargers at a bit of a distance, and there are half a dozen relative-convenient non-Tesla chargers a 10 minute driver away. Charging at home isn't necessary, but it would be very convenient and give me peace of mind.

https://www.amazon.ca/gp/product/B0163AKLK4/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Let me know what you think! I noticed one thread about 120v causing a short circuit? I have zero understanding of either physics or electrics so I just want to know if this plan carries any risks. thanks!!

I used to charge at work using 120v. If the temperature got below freezing the car used almost all the energy keeping the battery warm enough to charge so all I succeeded in doing over a 12 hour period was keeping the battery warm...
 

Fadiawesome

Member
Sep 8, 2019
153
93
IDAHO
I used to charge at work using 120v. If the temperature got below freezing the car used almost all the energy keeping the battery warm enough to charge so all I succeeded in doing over a 12 hour period was keeping the battery warm...
interesting, I do this, and my car still. charges at a rate of 2% an hr, its just that the next day I have a cold battery and snowflake icon on my battery. also for the op, I use a 50ft extension cord I bought from Walmart, and it works fine.
 

nwdiver

Well-Known Member
Feb 17, 2013
7,786
10,027
United States
interesting, I do this, and my car still. charges at a rate of 2% an hr, its just that the next day I have a cold battery and snowflake icon on my battery. also for the op, I use a 50ft extension cord I bought from Walmart, and it works fine.

At < 32F? If it's > 40F it does great. Colder temps not so much.
 
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Fernand

Active Member
Mar 22, 2019
1,493
1,499
Northern california
No short circuit. The thickness of the wire plays a big role in efficiency. With a good enough cord you lose virtually nothing over a 50ft run at 120 volts 12 Amps. Ive always gotten 5 miles charge per hour with this 12 gauge 50 ft cable. I use it all the time. Your 10 gauge choice is even thicker. Temp is another matter. In Northern California it can get down to freezing though not often. But I don't remember Vancouver being 24x7 polar. I think it would be OK as the backup you want.
.
 
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BEPA400

Member
May 1, 2019
341
270
Canada
Ha. You probably live within 5 minutes of me. I have exactly the same situation. I have a couple 12/3 awg extension cords, 50 foot and 100 foot. I’ve been charging like this since 2016. You don’t need 10 gauge for 50 feet, but it will save you a bit over the years in energy loss. My 12/3 100’ voltage at car drops from 120v no load to about 110-112 at 12amps.

there is one extension cord 12/3 at Costco downtown that is pretty cheap and would work well for you.


Hi everyone! People were super helpful on my first general-tips post, so I thought I'd shoot out another with a more specific question. I've looked through the existing threads and haven't found all that much that's applicable to my situation.

General question: Is charging from a 120v (regular house plug) with a 50' extension cord problematic?

Specifics: I live in a shared house and the (open-air) parking spot in the back lane is far from the nearest plug. I am only here for another 7 months or so, so I have no plans to install a wall-charger. I think the spot is about 50' from the regular 120v outlet on the wall at the outside of the house (there is not an additional dryer charger). I've found a 10-gauge, 15 amp cord that looks (and is priced) quality and will cover the distance - see the amazon link. I live in Vancouver, so there are some super-chargers at a bit of a distance, and there are half a dozen relative-convenient non-Tesla chargers a 10 minute driver away. Charging at home isn't necessary, but it would be very convenient and give me peace of mind.

https://www.amazon.ca/gp/product/B0163AKLK4/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Let me know what you think! I noticed one thread about 120v causing a short circuit? I have zero understanding of either physics or electrics so I just want to know if this plan carries any risks. thanks!!
 

BEPA400

Member
May 1, 2019
341
270
Canada
Ah I just noticed you say 7 months? Definitely don’t bother with a 10/3! 12 gauge for the win here..

And charging at home isn’t NECESSARY. But parking in the alley/yard in east van I like leaving sentry mode on. You wouldn’t believe how many sketchy people do bad *sugar* around here at night. So I leave the car plugged in to power sentry mode basically..

One risk to be aware of if you are plugging and unplugging regularly from the wall/extension cord, pay attention to each connnection to make sure they’re tight. And periodically check them after a couple hours of charging to check for heat. Warm is normal but if it’s too hot to touch you have a bad connection and risk of fire..
 
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Kevin-rf

Member
Oct 12, 2018
102
87
New England
Looks like this won't be a problem for you, but when you run the cord, make sure you don't coil any excess, like on a spool. I had a kiddo do that with a space heater and melted the cord onto the spool. The more airflow around the cord, the better, the cord will be slightly warm.
 

Gasaraki

Active Member
Oct 21, 2019
1,546
1,019
Syracuse, NY
Hi everyone! People were super helpful on my first general-tips post, so I thought I'd shoot out another with a more specific question. I've looked through the existing threads and haven't found all that much that's applicable to my situation.

General question: Is charging from a 120v (regular house plug) with a 50' extension cord problematic?

Specifics: I live in a shared house and the (open-air) parking spot in the back lane is far from the nearest plug. I am only here for another 7 months or so, so I have no plans to install a wall-charger. I think the spot is about 50' from the regular 120v outlet on the wall at the outside of the house (there is not an additional dryer charger). I've found a 10-gauge, 15 amp cord that looks (and is priced) quality and will cover the distance - see the amazon link. I live in Vancouver, so there are some super-chargers at a bit of a distance, and there are half a dozen relative-convenient non-Tesla chargers a 10 minute driver away. Charging at home isn't necessary, but it would be very convenient and give me peace of mind.

https://www.amazon.ca/gp/product/B0163AKLK4/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Let me know what you think! I noticed one thread about 120v causing a short circuit? I have zero understanding of either physics or electrics so I just want to know if this plan carries any risks. thanks!!

No. I've tried that before and it works just fine. The charge rate is dirt slow (1kw) but it works.
 

MN3SRPlus

Member
Jul 7, 2020
7
16
St Paul, MN
Can you check the breaker panel and see what amp that circuit is?

It should be either 15 or 20. If it is a 20 amp breaker, and there are no other items sharing the circuit, you can buy the 5-20 adapter for the Universal Mobile Connector that comes with the car ($35 US) and get a 20 amp extension cord. You may also need to swap the existing receptacle for a 5-20 one. Good quality, weather resistant, GFCI outlets can be had for $20-$30 US. If you can do this, you will be able to deliver 30-40% more power to the car than using the 15 amp setup that comes standard.

15 vs 20 amp at 120v may not seem like a big difference, but it does add up over time. At 15 amp you might be able to add 13-14 kwh to you pack in 12 hours, at 20 amp you. should get 19+ kwh in the same time. Also, as others mentioned above, the car will need more energy to warm the pack as in gets colder and the 20 amp setup will buy you a little more time.

The cost difference is maybe $50-$100 but it is a pretty good return on investment.
 
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jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
8,258
9,122
Riverside Co. CA
interesting, I do this, and my car still. charges at a rate of 2% an hr, its just that the next day I have a cold battery and snowflake icon on my battery. also for the op, I use a 50ft extension cord I bought from Walmart, and it works fine.

Murrieta CA doesnt spend a ton of time in temps that are actually "cold" ( I live in temecula, on the border of murrieta so am very familiar with the temps here). It does get to low to mid 30s overnight, but when people are talking about "cold" they usually talking about temperatures that are much lower than we see here.
 

ai4px

Wes
May 2, 2018
447
478
Sumter SC USA
Id like to offer a different perspective here... the electric outlets used in residential and commercial are not rated for thousands of plug in cycles. Hospital grade outlets are better. The 50amp RV plugs aren't even meant for thousands of insertion cycles. You know what plug is rated for 10,000 insertion cycles? J1772.

Here's the issue... receptacles get loose... and when loose they can get hot. Every EVSE I know of (well the good ones) measure temperature at the plug. Tesla Gen 2 UMC does. The GM branded unit that comes with Chevy Bolt does. When you use an extension cord you remove the ability of the EVSE "charger" to see the temperature of the plug that is most likely to have been used and abused... the one of the side of the house. Instead your "charger" can only measure the temperature of that new extension cord you just bought.

If you must use an extension cord, please buy a J1772 (or tesla) extension cord and leave the EVSE connected directly to the wall socket.

And one more thing... many electricians use "stabs" on the back of the outlets instead of the screw terminals. You might want to check that the outlet (and all others on that same circuit) are using screw terminals.
 

ShaolinJ

Member
Aug 5, 2020
58
37
Las Vegas
See if you can find a nema 5-20 outlet - google it if you dont know what it looks like, it looks like a regular outlet but has an extra horizontal notch. This improves your charging speed enough for it to be perfectly acceptable unless you are driving a lot of miles. You can buy a nema 5-20 extension on amazon and your charging speed is about 5-6 miles an hour, so a typical 10 hour overnight charge will give you 50 miles or so.
 

EmilyLC

Member
Dec 7, 2020
8
4
Vancouver
You're not the black tesla across the street I saw charging with an extension cable through the front door are you? I've been thinking about just knocking on their door and asking!
 
Oct 28, 2019
256
222
Texas
do *not* use a walmart extension cord to charge... just don't.

get a contractor grade heavy duty 10 gauge / 15amp rated cord and you won't see much loss and no fire risk. many of them are UL listed and USA made. cheap extension cords get scary quickly.
 
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EmilyLC

Member
Dec 7, 2020
8
4
Vancouver
Id like to offer a different perspective here... the electric outlets used in residential and commercial are not rated for thousands of plug in cycles. Hospital grade outlets are better. The 50amp RV plugs aren't even meant for thousands of insertion cycles. You know what plug is rated for 10,000 insertion cycles? J1772.

Here's the issue... receptacles get loose... and when loose they can get hot. Every EVSE I know of (well the good ones) measure temperature at the plug. Tesla Gen 2 UMC does. The GM branded unit that comes with Chevy Bolt does. When you use an extension cord you remove the ability of the EVSE "charger" to see the temperature of the plug that is most likely to have been used and abused... the one of the side of the house. Instead your "charger" can only measure the temperature of that new extension cord you just bought.

If you must use an extension cord, please buy a J1772 (or tesla) extension cord and leave the EVSE connected directly to the wall socket.

And one more thing... many electricians use "stabs" on the back of the outlets instead of the screw terminals. You might want to check that the outlet (and all others on that same circuit) are using screw terminals.

So I'm not quite sure I follow you, but after looking more closely at the Tesla Gen 2 connector that came with the car, I'm realizing I have 20 feet of cord with the Nema adaptor to plug into the 120v wall socket. So is your suggestion to get more of the same kind of cord, use the Tesla adaptor in the wall? Tesla's store doesn't have an extension cord, so I'm not quite sure what kind of cord I'd need to add between Tesla's wall adaptor and the original 20' cord. Sorry for my utter ignorance of electronics I just find it all very confusing!
 

trm2

Active Member
Apr 3, 2016
1,050
1,640
CLE
What do you know about the outlet? Is it alone on the circuit or does it share with other outlets? If shared, it can be easy to trip the breaker.
 

EmilyLC

Member
Dec 7, 2020
8
4
Vancouver
What do you know about the outlet? Is it alone on the circuit or does it share with other outlets? If shared, it can be easy to trip the breaker.
I have to check on that. There are two (double) outlets on the back outside wall of the house none of which are in use. But the more convenient outside outlet might be on the same circuit as some of the downstairs lights. Will check with my roommates on that since I only just moved in. Thanks for reminding me about that :)
 

UncleCreepy

Member
Mar 29, 2020
201
322
Lunenburg, ON
What @ai4px said. Avoid using an extension cord, it's not safe. It will likely work, at least for a while, but without monitoring the temperature at the outlet you're creating a ticking time bomb. There is a reason why the UMC has a temperature sensor built in. Going outside and checking the temperature every now and then is just not feasible. If it starts melting, it will happen fast, and you probably don't want to spend your time sitting next to the outlet with your hand on the plug.

From the UMC manual:
Warning: Do not use an extension cord, a multi-outlet adapter, a multi-plug, a conversion plug, or a power strip to plug in the Mobile Connector.
 
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