Extension cord for charging at 110V?

[eprosenx]

okay guys....update.....picked up a 15', AWG 12/3 SJTW extension cord at Lowes, rated at 15A/125V/1875W. Trying it in my garage for a few hours, connected to the long Tesla cord and adaptor. I'm charging at 113V, 12A....getting 4 mi/hr. Looks good so far, less voltage drop than before as you all predicted. Should be safe for extended time at 12A I'm assuming.....but will run a bit and see if the plug ends heat up again.

Again, I'm just looking for something I can store in the car, to top off my charge with when visiting relatives for overnight stays.....without burning down their houses!

Love it! Nice!

I really would recommend buying the NEMA 5-20 adapter from Tesla for $35 as well. You won’t regret it when you find a place you can charge 50% faster just by having that adapter.

And then also that NEMA 5-15P to NEMA 5-20R adapter I linked to on Amazon. The combo of those two things can make a huge difference in some charging situations. But you have to be very careful with that adapter from Amazon.

This is my full set of adapters, but in reality, I never need most of them (I actually have even more than displayed here). I just like being prepared for anything.

 

[Superman910]

Love it! Nice!

I really would recommend buying the NEMA 5-20 adapter from Tesla for $35 as well. You won’t regret it when you find a place you can charge 50% faster just by having that adapter.

And then also that NEMA 5-15P to NEMA 5-20R adapter I linked to on Amazon. The combo of those two things can make a huge difference in some charging situations. But you have to be very careful with that adapter from Amazon.

This is my full set of adapters, but in reality, I never need most of them (I actually have even more than displayed here). I just like being prepared for anything.

View attachment 396520

This *sugar* is epic.

Is that a plug and play Nema 14-50 in the left hand corner?

 

[eprosenx]

This *sugar* is epic.

Is that a plug and play Nema 14-50 in the left hand corner?

Lol. Yup. Just point me at the breaker panel.

I have 50a breakers for several different brands. I also can just tie into an existing breaker too like some random 30a for a dryer or something.

I now also have California connector to nema 14-50 adapters and such too. And a 10-50 for old range plugs.

But note I almost never use this stuff. It was a hobby for me while waiting for my car (and the direct wire setup was from 2012 when I helped a friend with an S with some temporary charging needs).

I just hate having my car limit me. I basically never stop at superchargers because most of my weekend trips are within a few hundred miles of home and I can figure out how to charge just about anywhere overnight as long as I have permission to mess with the electrical system.

 

[linkster]

Such good advice given already. I experimented with extension cord charging up to 300' six years ago, and often send 240v thru the above mentioned extension cords (that’s a topic for another day). I also have 3 extension cord charging kits ranging from a lite 20/16a, medium 30/24a, and a heavy duty 50/40a, however, that does not make me an expert in any way. Just a little concerned that you have such a limp 108v instead of a nice stiff 125v. Personally, I always seek out a dedicated receptacle such as a washing machine, microwave, or a duplex that is close to the load center that is not daisy chained at the end of a branch circuit. I never leave the extra coils of extension cord neatly bundled together to aid in cooling. I check for excessive heat at 5 min, 20 min, and 60 min at all connection points. If I don’t have time to verify the integrity of the entire branch circuit, I will manually dial down my amperage to seek the range I need over my time parked.

Some of my lite gear includes a 25' 12/3, 50' 12/3, 100' 10/3.

Opps, I forgot to mention that I carry my @TonyWilliams stretched 50' UMC in the S and my stretched 40' UMC in the 3.

Tesla and I both recommend that you don’t use an extension cord for charging.

 

[eprosenx]

Such good advice given already. I experimented with extension cord charging up to 300' six years ago, and often send 240v thru the above mentioned extension cords (that’s a topic for another day). I also have 3 extension cord charging kits ranging from a lite 20/16a, medium 30/24a, and a heavy duty 50/40a, however, that does not make me an expert in any way. Just a little concerned that you have such a limp 108v instead of a nice stiff 125v. Personally, I always seek out a dedicated receptacle such as a washing machine, microwave, or a duplex that is close to the load center that is not daisy chained at the end of a branch circuit. I never leave the extra coils of extension cord neatly bundled together to aid in cooling. I check for excessive heat at 5 min, 20 min, and 60 min at all connection points. If I don’t have time to verify the integrity of the entire branch circuit, I will manually dial down my amperage to seek the range I need over my time parked.

Some of my lite gear includes a 25' 12/3, 50' 12/3, 100' 10/3.

Tesla and I both recommend that you don’t use an extension cord for charging.

Great advice! Yeah, so most wire is rated up to 600v (some is only 300v - when you have a “J” in the code on the side for “Junior”). So yeah, would have zero issues using that cord at 240v.

Did you do your 16/20a charging on 12 gauge wire? Should be fine since that is what the NEC rating is anyway and a cord in free air laying on the ground can probably dissipate heat better than wire in the wall. 12 gauge is probably overly cautious for 12a charging, but still a great idea. I would likely be tempted to try that cord using the adapter I linked to at 16a if the situation arose and I could monitor it.

As stated many times, this is not something you want to do for normal charging, but in a pinch it is fantastic to have the options!

P.S. Your advice on using dedicated circuit receptacles or the receptacle that is first in the chain (usually closest to the load center) is SPOT on. I do the same and it is fantastic advice. Laundry circuits (dedicated 20a) and microwave circuits are fantastic choices (typically not daisy chained). Kitchen circuits are daisy chained, but they are 20a so also good choices. Garage circuits are often but not always 20a.

 

[linkster]

Did you do your 16/20a charging on 12 gauge wire?

Yes, 12 is the smallest I deploy. Personally, I will gladly use a longer extension cord to reach a known dedicated receptacle.

Those of us dinosaurs had to charge by any means necessary back in the day before supers and destination hosts.

Don’t use extension cords for EV charging.

 

[puckpurnell]

Responding after reading all of this because I’m planning on leaving my M3 at a friend’s for 10 days while I’m out of the country. Decision: charge to 90% and leave the car ; charge to 50% and then use the Tesla supplied 110 plug with a 20’ 12/3 extension cord and leave the car plugged in for the duration of the trip. Advice please.

 

[hcdavis3]

Responding after reading all of this because I’m planning on leaving my M3 at a friend’s for 10 days while I’m out of the country. Decision: charge to 90% and leave the car ; charge to 50% and then use the Tesla supplied 110 plug with a 20’ 12/3 extension cord and leave the car plugged in for the duration of the trip. Advice please.

I’d go with 110 while you’re on your trip Puck.

 

[kavyboy]

Responding after reading all of this because I’m planning on leaving my M3 at a friend’s for 10 days while I’m out of the country. Decision: charge to 90% and leave the car ; charge to 50% and then use the Tesla supplied 110 plug with a 20’ 12/3 extension cord and leave the car plugged in for the duration of the trip. Advice please.

I would charge to 90% then make sure sentry mode is off, and not keep waking it up by check it remotely. I personally would be uneasy leaving an extension cord plugged in unattended for that long. You should have plenty of charge unless your friend's place is far from the nearest supercharger.

 

[evM3Sekar]

I’d go with 110 while you’re on your trip Puck.

I always leave it plugged in (in my garage) with the UMC on the 120v/15a outlet, charging from 70% to 80% on a daily basis. For long trips (10-14 days), I plan to leave it plugged in but set the charge limit to 50% (or 60%), but then one day before I come back set the limit back to 80%. The intent here is to avoid keeping high charge when the car is not being used. Am I overthinking this?

It's likely that battery charge may not drop from, say, 70% to 50%, in spite of setting the lower limit, because the car will draw power from the wall for its chores when plugged in. Will report on this after my 12 day trip in the first half of May.

 

[dhrivnak]

I'm traveling to my son's home to visit for Easter.....and will do some slow charging via 110V plug in his garage. I had never charged with 110V, so tested out in my garage outlet today. Plugged in, at 108V was getting 12A charging and 4 miles/hr. I was using a 25' orange extension cord from my outlet to the Tesla cord and adaptor. After letting it charge for about 4 hrs, I unplugged it and both ends of my extension cord were warm.....not hot, but definitely warm.

My extension cord is just a standard orange 3-prong outdoor rated cord you can buy in Home Depot. Is this warmth normal....or should I be using a certain higher rated extension cord.....and if so, what type? Just want to make sure I don't burn down my son's house.....that would not be a good thing.

Warm is an indication of a problem. You need to have a heavy duty extension cord, ideally 12 gauge for EV Charging it can work and I have done it but I also only use heavy duty cords.

 

[linkster]

Responding after reading all of this because I’m planning on leaving my M3 at a friend’s for 10 days while I’m out of the country. Decision: charge to 90% and leave the car ; charge to 50% and then use the Tesla supplied 110 plug with a 20’ 12/3 extension cord and leave the car plugged in for the duration of the trip. Advice please.

Personally, without knowing how robust that particular branch circuit is, I would manually lower the charge rate to 5a to minimize any potential charging issues.

Tesla reccomrnds agsinst using extension cords.

 

[puckpurnell]

Great advice all around. Thanks to ALL. I’ll definitely lower the amperage. Saw another thread warning to turn off cabin fan. My friend will be available to check for any heat in the 12/3 cord. She can alert me and I’ll just stop the charge from my phone. Again, thanks for the help.

 

[TexasEV]

For long trips (10-14 days), I plan to leave it plugged in but set the charge limit to 50% (or 60%), but then one day before I come back set the limit back to 80%. The intent here is to avoid keeping high charge when the car is not being used. Am I overthinking this?

Yes. Tesla recommends this for long term storage, but that’s months, not days.

 

[Dan123]

I used an extension cord for 120v. The first one I used got warm. I went to Home Depot and bought this one, and it worked without getting warm. I also got a little bit more power out of the second one (the power that was not wasted on warming the extension cord).

 

[linkster]

I always leave it plugged in (in my garage) with the UMC on the 120v/15a outlet, charging from 70% to 80% on a daily basis. For long trips (10-14 days), I plan to leave it plugged in but set the charge limit to 50% (or 60%), but then one day before I come back set the limit back to 80%. The intent here is to avoid keeping high charge when the car is not being used. Am I overthinking this?

It's likely that battery charge may not drop from, say, 70% to 50%, in spite of setting the lower limit, because the car will draw power from the wall for its chores when plugged in. Will report on this after my 12 day trip in the first half of May.

Usually, I agree with Tex, however, if you are like me that keeps their equipment and cars in top condition forever, you are not necessarily “overthinking this”. If you flip cars every 4 years, it really won’t make much of a difference. I don’t really abide by the Telsa manual WRT daily charging, storage charging, tire pressure, alignments since:

a) it is written by overworked by very smart youngsters
b) it is written by smart techy youngsters with little to no real world mototsports experience
c) It’s an attempt to keep things simple
d) we now have experience and long term data to draw upon

I have lost 8 miles (shown) of range in a little more than 6 years and ~85K miles deploying a nightly 70 - 40% SOC strategy with a mostly 80-mile RT commute and then sitting at 50% SOC if she is not going to be driven for a couple of days or more. I am not suggesting that others follow my fusspot ways, but the six-figure S was 3X more expensive than any other daily driver we have ever owned and I enjoy treating her with extreme TLC and I will continue to do the same for her 1 year old lil' sister 2170 cell powered M3.

 

[Petrlol]

Lol. Yup. Just point me at the breaker panel.

That portable 14-50 is legit.... I don't know whether it's amazing or sad...
Here I am hoarding adapters and getting glances from the wife anytime a random cord shows up from amazon, and you're packing breakers around...

 

[GRNN_Coco]

Love it! Nice!

I really would recommend buying the NEMA 5-20 adapter from Tesla for $35 as well. You won’t regret it when you find a place you can charge 50% faster just by having that adapter.

And then also that NEMA 5-15P to NEMA 5-20R adapter I linked to on Amazon. The combo of those two things can make a huge difference in some charging situations. But you have to be very careful with that adapter from Amazon.

This is my full set of adapters, but in reality, I never need most of them (I actually have even more than displayed here). I just like being prepared for anything.

View attachment 396520

I love your charging kit ! Could you please share the link(s) where to buy those ? I really appreciate.

 

[linkster]

Love it! Nice!

I really would recommend buying the NEMA 5-20 adapter from Tesla for $35 as well. You won’t regret it when you find a place you can charge 50% faster just by having that adapter.

And then also that NEMA 5-15P to NEMA 5-20R adapter I linked to on Amazon. The combo of those two things can make a huge difference in some charging situations. But you have to be very careful with that adapter from Amazon.

Agreed, yes, the Gen I UMC 5-20 and the Gen II MC 5-20 are terrific versatile adapters. I believe that everyone should at least carry a 5-20, 10-30, and a 14-30 adapter along with the amazon adapter as well. For general safety practices, might we be able to refrain from discussing modding a particular adapter? (for those that know what I am referring to)

 

[knects]

Love it! Nice!

I really would recommend buying the NEMA 5-20 adapter from Tesla for $35 as well. You won’t regret it when you find a place you can charge 50% faster just by having that adapter.

And then also that NEMA 5-15P to NEMA 5-20R adapter I linked to on Amazon. The combo of those two things can make a huge difference in some charging situations. But you have to be very careful with that adapter from Amazon.

This is my full set of adapters, but in reality, I never need most of them (I actually have even more than displayed here). I just like being prepared for anything.

View attachment 396520

I particularly like the included brass knuckles you have integrated. Could come in handy.