Amazon.com: 100 foot 12 gauge extension cord. SIMBR 100 FT 12/3 Extension Cord Outdoor/Indoor, Heavy Duty Electrical Cord with Lighted 3 Outlets, 3 Prong, 15 Amps, UL Listed, SJTW - Power Your Household, Office and Garden Electric Appliance. 4.7 out of 5 stars 39.

• Woods 100-foot Extension Cord 12 Gauge

Woods 100-foot Extension Cord 12 Gauge

I live in a 1940’s LA rental that has a garage with no power, and only a 120v plug in my apartment 60 ft away.Landlord won’t allow any power hookups in the garage, but I have free charging at work so I’ve been fine - except I just got a film directing job abroad for 2 months. Obviously I’ll need to keep my car plugged for that long a time, so I just ran a 100 ft 13A outdoor extension cord between my apartment and garage.Tested overnight and my M3P charged consistently at 115v, 12A, and 4 m/h. Cord didn’t get warm, including the female end. So all seems fine for trickle charging. Liking the setup so much I’d like to use it regality. But i have a few concerns:- Manual says to not use an extension cord.- I did have to coil up a good 10 ft of the cord.- After fully charged, charging would start up again every hour or so, presumably from phantom drain. Seems like a lot of stops and starts.

Not sure if that’s normal. Doesn’t happen with the L2 charger at work.- The slow charge is probably inefficient.Anyone else have a similar setup and have any thoughts/tips?

Hey Meni,I used to charge my Model 3 w an extension cord. What a lot of people don’t seem to know, you can keep the car plugged in without charging it.

If you’re leaving for 2 months, I would suggest you charge it up to 80% and leave it plugged in, but stop charging it. That way you’ll only lose your phantom drain, but your car will be plugged in the entire time as Tesla suggests. A lot of people don’t same to be aware that just because it’s plugged in doesn’t mean you have to be charging. I would think this would have less “wear and tear” to interior components when left a period of time without use, vs it starting and stopping to top off a charge you don’t need once an hour for 2 months. After working in this field for more then 20 years, first it's always the weakest link that will cause your problems.

You can have a 12 AWG extension cord wich is good for a 50 ft (for a 115Vac use at 15 amps max) but if you have a mecanical issue like bad connection between the wires and the pins in the plug then your plug will heat. If you have bad connection due to bad pin contact (like dirty pins or corroded) then it will heat up.

In the beginning I used to charge only on 120V for several month. I used a 10 gauge 100Ft extension cord and this worked fine. Even leaving it plugged in for 2 days. You will have to use 10 Gauge to be safe and do not leave any coiled up at all.

I would lower the charge current to 8 Amps just as another safety. The car will use power from the grid to do its 'overhead' functions, and may use some from the battery and then recharge, but all of this will work fine and the car will take care of itself for the 2 months as long as it is plugged in. Anything could happen.

A rat could chew through the cord and start a fire. But that could happen with Christmas lights as well. I have had my BMW trickle charging (Starter battery) since the beginning of the year with a 50 ft extension cord.My recommendation.1) AmazonBasics 12/3 SJTW Heavy-Duty Lighted Extension Cord.2) Lower charge current to 5amps (If it goes that low)3) Optional: Set schedule charging start time to the middle of the night when it is cool.Even a 120v/5 amps you should never need to charge for more that a couple of hours at a time.On that note, start with the car charged to at least the level of the charge limit. Thanks for all the great info. A bit more about my setup:- Both ends of the plug are indoors, dry and secure.- While in LA I charge 3-4 hrs in the early morning (when it's coldest).- Work is 4 miles away so no need to charge more than that.- For my 2 months away I'll plug in but not charge right away. Will remotely charge for an hour or so a couple times a week for phantom drain and battery health.- I'll ask my neighbor check in the wiring.Seems I should be okay, especially of I drop to 10A while away. @Bighorn, @mrburke, I did say it 'may' use power from the battery at times!

I do not dispute that at all. The following is how I experience this. I use the timer to charge, it will not charge at all until that time comes around again every 24 hours no matter what. If there is a power outage it will not re-start to charge until that time comes again.

This said the car can choose what and how to do. I do notice the T by the charge port turning solid green every so often during the day while parked at home and plugged in.

Solid green is an indication of it using power from the grid and blinking is indication of battery charging. Also when I turn the pre-heat on in the morning, )charging is complete) the charge port will go from white T to solid green T and provide power for that. I have always found the charge to be at set point when plugged in, which is another indication of it using grid power for overhead functions while plugged in. @Bighorn:'Sounds like s horrible idea.' LOL!So to you plugging a high power draw appliance into an extension cord that runs 100 feet outdoors to a building built in the 1940s an leaving it that way unattended for 2 months is perfectly reasonable?But disconnecting a car's 12V battery so that its computer, modem and other devices don't drain the battery when it won't be used for a long time is a 'horrible idea?' I guess having the means to buy a professional degree is not a guarantee that someone is capable of actual thinking.

120V/5A for a few hours once a week is a high power draw, professor? Pot isn’t legal in WY, so I’m having trouble following your logic. Unplugging the 12V will allow both the 12V and the HV battery to lose charge. There is no BMS minding the store, so nobody can plug in the car if there’s a SOC issue or move it if there’s an emergency. Are you going to put the 12V on a 100 foot trickle charger or bring it into the house? I guess Tesla needs you to rewrite the owners manual and amend the part about keeping it plugged in for optimal health.

But if you can’t actually think, go ad hominem. @Bighorn:'120V/5A for a few hours once a week is a high power draw, professor?'

BTW, how did you come up with your '5A for just a few hours once a week' numbers? Did you just pulled them from thin air to try to make your point? You know for a fact that a Model 3 plugged into a 100 ft extension cord plugged into a 120V outlet will only draw 5A for a few hours once per week?Isn't it enough that Tesla explicitly tells people not to do this?

You really have to try to convince people that you know better than Tesla's engineers? Recharging is prompted by an 3% drop in absolute SOC or about 2 kW. This drop takes about six days in my Model 3. To add back the 3%, roughly 2kWh at 600W takes slightly over 3 hours. If I left my car at 90% SOC and set the car to maintain at 50%, the car would not charge for the 3 hours until day 80, which if my math is correct is not within a two month time frame.

Ipso fatso, there is no current in the extension cord ever. An extension cord can be more robust than the wire in the wall, so the admonition is for the folks who need warning labels to prevent Darwinism. I think my initial advice to not overthink it was rather prescient. Fortunately, the OP seems like a reasonable guy. @BighornYou still haven't answered the question how you came up with your made up '5A' number.The UMC charges the Model 3 at about 5 miles per hour.

Since we know each mile is 220 Wh that's at a minimum 1,100W. If you factor in the considerable loss your going to get running over old building wires and a 100 foot extension cord the amps pulled is probably going to be at least double your made-up number and maybe more.I'm probably underestimating the line loss above. And do you know where that loss goes? It turns into heat in your wiring. Old building wires often don't like heat.

And it's not just the gauge of the wiring that's important. Often the problem heat is generated at the plugs. And with an extension cord you're doubling the number of plugs.Let's put it this way: Charging the Model 3 over 120V works in about the same range as electric space heaters. Electric space heaters work at about 750 - 1,500 watts.

Do you know what often happens when you mix electric space heaters with extension cords? Particularly in buildings with old wiring and plugs?A lot of people have burned down their houses this way. And, by the way, the longer the extension cord the worse the problem.

100 feet is a very long extension cord.@OPI am not an electrician or electrical engineer and neither is @Bighorn. @Bighorn says you can ignore Tesla's warning about never using an extension cord with your car because 'the admonition is for the folks who need warning labels to prevent Darwinism.'

You need to decide if you're one of those folks who prove Darwinism by ignoring warning labels.There's a good chance you'll be fine for 2 months with your extension cord. But there's also a chance you won't. I know what I would decide if it were my house and my car.

Make your choice. @carl and bighorn. Really both of you are correct in your own way. There is not any guidance other than Tesla saying no extension cords. Since the OP is ignoring that recommendation then it’s really a lot of “if’s” and “what’s”.And yes the 12v could lose enough charge in 2 months to be dead disconnected.All this discussion brings up a good point though. Why isn’t there a way to turn the car off?

Like powering down a computer or smart phone. Let’s face it these things are basically a computer on wheels.My 0.02: any time we leave our house or condo unattended for more than a week I unplug or turn off the breaker on all the appliances.

We once had a dishwasher spontaneously catch on fire when we were in Hawaii for 3 weeks. Luckily we have a monitored alarm system and my Mom had a key to let the fire department in. Also lucky for us it smoldered and put out a ton of smoke and they got there before it ignited the house. So personally I wouldn’t leave our Tesla plugged in for 2 months, in our garage, in our house that is 15 years old. @Bighorn ' Preheating the car will draw from the battery and the wall cord will concomitantly refill the battery.' I'm not disagreeing with you. I think I just look at it different.

Let me explain. If I take a fully charged 12V battery, hook it to an automatic battery charger, the charger will not charge. Now I hook a load to that battery while the charger remains hooked up, the charger will now put out about what I use. Does it now actually re-charge the battery or is it supplying power to the load? @Bighorn My 12V battery deal was just an example, trying to explain how I look at it as a battery has load on it and a charger providing power to it at the same time, not saying this is in the car.

I'm aware that the heater is an HV heater and uses power from the HV system in the car and not from the little 12V battery, actually the 12V system will have to supply power to in order to make this all happened, but this just adds a little to the load. By the way, I'm not aware that Model 3 has a battery heater like Model S does. Anyway, if the car the charger provides power to the HV battery and at the same time the car is using power from the HV battery, if the supply and load are equal is it really using the battery or is it just using the power provided by the charger?

@Bighorn For most overhead functions the power usage is minimal and most likely would not exceed the charger. In case of running the heater it is possible. The following is out of Model 3 owners manual: 'Note: Whenever Model 3 is plugged in but not actively charging, it draws energy from the wall outlet instead of using energy stored in the Battery. For example, if you are sitting in Model 3 and using the touchscreen while parked and plugged in, Model 3 draws energy from the wall outlet instead of the Battery.' For all you non-electricians.The cords are rated at a certain amp because of allowable voltage drop regulations.You will not burn up a brand new extension cord if its rated at 13 amps and you run 15 through it.It also doesn't matter how long the cord is for heat dissipation.

A 10 gauge cord running 13 amps will produce the same heat per foot for a 10 foot cord or a 1000 foot cord, same amount of current through the cord no matter the length. Its the voltage drop at the other end that would be affected.You get fires from extension cords from shorts or breaks causing localized heating.That said, if you are drawing current and the voltage drops you WILL see a reduction in charge rate.I would not use a small gauge cord for long distances because of that.

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