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Charging on NEMA 5-20 at 7mph!

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What do you consider a short run? I use a 75 foot extension cord at my kids that is #12 wire, which is good for 20 amps. The 5-20 draws 16 amps continuously. Most extension cords are #14 wire which is only good for 15 amps, hence they will overheat. Add distance and voltage drop and you aggregate the situation even more.
Almost all extension cords even 12G are not safe for charging particularly long ones, the ends are poorly manufactured. If you are doing this is is better to use your own ends not the crappy ones supplied, they all are. I would not do a run like this without using 10G and commercial ends as you don't alway s know the length of the downward line and its outlets and terminations. Unless you can't make it to a charger I would not even charge on 120V. 16A is the MAX load of a HEALTY 20A circuit. Anyone that has a dedicated 5-20 outlet should just have it properly converted to a 6-20 by a qualified electrician and if it's not a dedicated 5-20 you should not be using it.
 
Every over molded cord on Amazon is not good for EV charging, the end terminations and strain relief are junk
I truly am my handle, so I set up my charging off an outside NEMA 5-15 GFCI outlet that has only run a small water fountain pump. I have a 10g 15' cord
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that runs over a short wall to a driveway where I have plugged in the Tesla charger that came with my M3.

While not an 'optimal' situation, so far so good? We drove 50 miles last night for a dinner and my M3LR has been charging for close to 12 hours straight. The M3 is still charging, I just walked out and the extension cord is not warm to the touch at the outlet.

I'm not sure what the major risks are other than a possible outlet failure.
 
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Be careful about converting a 120v outlet to 240v unless you KNOW that only one receptacle is on that circuit. Usually 120V circuits have several receptacles daisy chained together.

There is nothing wrong with 120V, 20A charging. I did it for quite a while with my Model S. Worked great.

Probably shouldn’t be charging on an outlet that isn’t a dedicated circuit…
 
Every over molded cord on Amazon is not good for EV charging, the end terminations and strain relief are junk. To use in a pinch for an emergency is one thing but should not be used for regular use. They are all cheap even the more expensive ones.

I don’t agree. Note that EV charging is already derated since it charges at 16A instead of the rated 20A of the circuit. Additionally, I’ve been charging one of my EVs using a nema 5-20 for a long while and it works fine. Unless you have a specific story that happened to you, please stop scare mongering.
 
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I'm not a fan of using any extension cord for daily use. If it's your permanent home charging setup, pony up and get a proper outlet wired within reach of where you park your car. For reaching an outlet while at Grandma's, a well made extension cord makes sense.
 
What do you consider a short run? I use a 75 foot extension cord at my kids that is #12 wire, which is good for 20 amps. The 5-20 draws 16 amps continuously. Most extension cords are #14 wire which is only good for 15 amps, hence they will overheat. Add distance and voltage drop and you aggregate the situation even more.
25feet is my run....was looking for a reliable brand. Amazon had proper 5-20 cords rated for 20a but some reviews showed overheating and melted ends SPECIFICALLY when charging EVs. Seems more the connection of the wire to the prongs of the plug rather than the cord itself.

Wondering if itd be better to get a cord, cut the ends and add my own plugs.
 
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With 120V charging, it is also important to check the receptacle. Turn off the circuit breaker and unscrew, then inspect the receptacle and its wiring. If the wires are inserted via 'back stab' holes that use little knife edges to make contact, rewire using the screw terminals. You have to insert a very small blade into a slot to release the knife edge allowing the conductor to be removed. If the receptacle is commercial grade, the wire will be clamped by the screws in any case.

And speaking of commercial grade receptacles, homes are often full of el-cheapo 'residential grade' receptacles that come in 10-packs for like five dollars. When I first bought my house, I went through every switch and receptacle and replaced most of them. Some older ones were literally crumbling as I removed them. Commercial grade receptacles are not very expensive and far better constructed than residential grade.

As far as extensions go, I've both made my own - using SJOOW cable, and commercial grade plugs and receptacles, and also have a commercially made one for TT-30. With the TT-30, there are lots of off the shelf adapters in the RV world to go between 5-15/5-20 to TT-30 and back. On road trips I just carry the TT-30 extension with the adapters in case of emergency.
 
I truly am my handle, so I set up my charging off an outside NEMA 5-15 GFCI outlet...While not an 'optimal' situation, so far so good? We drove 50 miles last night for a dinner and my M3LR has been charging for close to 12 hours straight. The M3 is still charging, I just walked out and the extension cord is not warm to the touch at the outlet.

I'm not sure what the major risks are other than a possible outlet failure.
Have you bothered to calculate what you're paying in overhead costs to run the car's computers the entire time it's charging? Charging with NEMA 5-15 means you're using about 25% of the energy to power the computers. 240V at the same amperage would reduce that to about 10%. 240V@48A would reduce it to ~3%. The computers use a fixed ~300-400W, regardless of how much power the outlet is able to deliver, so the name of the game is to get the energy into the battery as quickly as possible and then let the car sleep.
 
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Have you bothered to calculate what you're paying in overhead costs to run the car's computers the entire time it's charging? Charging with NEMA 5-15 means you're using about 25% of the energy to power the computers. 240V at the same amperage would reduce that to about 10%. 240V@48A would reduce it to ~3%. The computers use a fixed ~300-400W, regardless of how much power the outlet is able to deliver, so the name of the game is to get the energy into the battery as quickly as possible and then let the car sleep.
Quite true. And if it is cold outside, you are getting almost no energy into the batteries since the car uses energy to keep the batteries warm. 5-15 is pretty inefficient, that’s why I always try to use 5-20 if I’m stuck with 120V. That’s also inefficient, but less so.