AZjeff
$50 Site Donor 2023
This Tesla owner recently moved into this rental house in our neighborhood. I suspect the heavy cord goes into a window in the laundry room and he's using the 240V plug at the dryer if that's possible.
How much extension cord is too much?
- Thread starter AZjeff
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JHZR2
Staff member
They make standard tables for current and gauge of cord.
Is that anything more than a 10-15A 120v charger?
Is that anything more than a 10-15A 120v charger?
AZjeff
$50 Site Donor 2023
I know nothing about EV charging but that's a really heavy cord coming from the back of the house. These houses have one or two 120v outlets in the garage.
I see lots of 240V extension cords in industrial for welders. I believe there either 8 or even 6 AWG. Technically there is nothing stopping 240V going down a extension cord. Usually you don't want it in residential for safety reasons.
If the cord is too long or too small it will effect the amperage at the car end. Definitely needs to be a large wire cord.
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I went with 6 AWG for my welder extension cord.
http://www.wiresizecalculator.net/
https://www.southwire.com/calculator-vdrop
http://www.wiresizecalculator.net/
https://www.southwire.com/calculator-vdrop
Could just be a heavy duty 120V cord.
Tesla is sensitive to voltage drops. My brother in law had my sister in law so mad when he cheaped out buying lower rated extension cord cheap for their barn before wiring it and EVs kept not charging impacting her. She had explicitly told him to research it (him PhD professor) and he definitely lied about it.
Tesla is sensitive to voltage drops. My brother in law had my sister in law so mad when he cheaped out buying lower rated extension cord cheap for their barn before wiring it and EVs kept not charging impacting her. She had explicitly told him to research it (him PhD professor) and he definitely lied about it.
AZjeff
$50 Site Donor 2023
Yes but would make no sense at all. These houses are built exactly the same by the same workers using the same wire and have 120V outlets in the garage. At least the guy is being safe parking it outside so it doesn't burn the house down.
I’ve always heard the you’re not supposed to use an extension cord with the EV or PHEV cord-charger.
They trip howver people do it including sister in law with her RAV4 PHEV where school custodian who likes her runs 120V cord to her car so she can’t get home for “free”.
If the cord is heavy enough, I don’t see an issue. The wiring in the walls is only so thick too.
Exactly - if it's charging his car, it's fine.
The real issue is length and what becomes "too long" leading to voltage drop.
Correct - the wire doesn't care, it's the plug ends that determine the voltage.
I’d worry more about the quality of the receptacles and how tight the connections are. Loose connections can create issues by increasing the resistance. A Tesla Mobile Connector will note that the plug is heating up excessively and will back off on max current. But more connections means a greater chance of a higher resistance point.
It’s rarely an issue if it just something using a tiny fraction of the max current. But with an EV you’re going to want at least 60% of the rated current.
It’s rarely an issue if it just something using a tiny fraction of the max current. But with an EV you’re going to want at least 60% of the rated current.
It’s a combination of things, but mostly about worst case (max rated current) and resistance per unit length. That’s the fire risk. But even then, the length will add to overall resistance and result in a voltage drop at the device.
I always ask perspective EV owners, "How ya gonna charge?" 120v nets 3-4 MPH. I accounted for charging well before buying the car.
I think the rest of the world uses 220-240V, so voltage is not really a problem if you keep the current low enough for the run. 240V 12A if you can is still going to be more efficient than 120V 12A, even if you have to run it from the window into the laundry room.
The best "hack" for charging EV's is to run a NEMA 6-20 outlet. All you need is 12 gauge wire and the appropriate breaker. If you have an existing dedicated 120V 20A outlet that was ran using 12 gauge, you might be golden. You can get about 3.8kw from this outlet -- which should be enough to give most smaller EV's around 100 miles of range during an 8 hr overnight charge.
AC and DC voltage drops are very different. That cord coming from an inverter\charger would be carrying DC, which needs big wires to transfer power over long distances.
If the cord was just plugged into a wall, the cord could be much smaller as it would be be carrying AC... and accomplish the same thing. That cord, cannot be anything bigger than 12GA,....not a "BIG" cord by any means
240 is easily obtainable in any house the the USA...not sure I see an issue.
He could run a dedicated circuit from the area in the house where it is plugged in.....in conduit and have a much smaller cord for charging.
Now that I am looking at the picture, I hope he does not start a fire.
If the cord was just plugged into a wall, the cord could be much smaller as it would be be carrying AC... and accomplish the same thing. That cord, cannot be anything bigger than 12GA,....not a "BIG" cord by any means
240 is easily obtainable in any house the the USA...not sure I see an issue.
He could run a dedicated circuit from the area in the house where it is plugged in.....in conduit and have a much smaller cord for charging.
Now that I am looking at the picture, I hope he does not start a fire.
You should get a temp gun.
