Extension cords

[RivkahChaya]

New member, new owner.

I actually found this site because I Googled "using extension cords with an EV" (or something), and it led me to an old thread, where the opinion was entirely schizmoid.

Apparently, once upon a time, people were specifically told on purchase not to use extension cords with chargers, but I was given no such advice. I was trying to decide whether a 12/3 standard cable or one that connected to my dryer plug would be better.

I understand that saying "Sure, go ahead," might lead some people to use the same cord they use for their bedside lamp, but electricity has no shape or taste-- all it needs is a cord that can handle the load. You get the same advice about space heaters-- don't use them, because people will use ones that are too light duty-- or use one of those grounding adapters.

If the extension cord is a low enough gauge, grounded, matched to the original in the amperage and voltage it pulls, and not so long that you lose too much power to the distance, or end up laying it over itself, I just can't see what the problem could be.

It's not like the electricity is special. You don't have a filter over it, or add anything to it--
Or do you?

But even if you did, isn't that happening at the plug?

[LeftieBiker]

The EVSE from Nissan, along with many other OEM units, has a temperature sensor built into the plug, to protect from overheating. Using an extension cord renders this extra layer of protection useless. So perhaps you'd consider rethinking your 'You people are idiots and I'm the sane one in the room' attitude...? I charge using an extension from necessity, but I don't tell myself that it's just as good or just as safe as plugging the EVSE in directly.

[knightmb]

As already mentioned earlier, extension cords are discouraged because they introduce extra points of failure. If you are well versed in eletronics and the science of electricity, then you can make a better determination of the risk, but not everyone that reads this public forum is. That's why I would not use store bought extension cords with an EVSE. They simply fail because the designs were never intended or tested for the long, continuous power loads that a EV can draw while charging. The only extension cords I would trust are the ones I make by hand and test. Amazon is full of extension cords for various EVSE, but it doesn't mean they are all safe. Most consumers wouldn't know a watt rating from an amp rating. If you know your science when it comes to electricity and electronics, no need to ask for our blessing. If you have a question of safety, many here will be glad offer input.

[RivkahChaya]

The EVSE from Nissan, along with many other OEM units, has a temperature sensor built into the plug, to protect from overheating. Using an extension cord renders this extra layer of protection useless. So perhaps you'd consider rethinking your 'You people are idiots and I'm the sane one in the room' attitude...? I charge using an extension from necessity, but I don't tell myself that it's just as good or just as safe as plugging the EVSE in directly.

Sorry if it came off as "I'm the only sane one"-- albeit, I was a power generator maint/mech in the army; it's not that much of a cred anymore, because it was back in the 90s, but extension cords are pretty simple.

And I didn't know there was a temp sensor built into the plug-- that's exactly the kind of info I was hoping to get by posting. Is it a shut-off sensor? and how does an extension cord defeat it, if the cord is between the plugs into the car and the wall?

If I use an extension cord, it will also be out of necessity. I will be renting a garage at my apartment complex, which has a 120 wall outlet-- on the ceiling, because the light also plugs into it-- I will be putting in battery operated lights, and unplugging the light, so nothing else draws from the outlet the car is plugged into, even though a light that looks to be about a 60W LED equivalent probably draws very little.

There is simply no way that the heavy cable that comes with the car, along with its even heavier adapter, will stay plugged in. It will either fall at once, and damage the roof or windshield, or fall slowly, and at some point be halfway plugged, and probably arc and start a fire.

I have been given permission both to install the battery-powered lights (stick them to the walls, in other words), and place hooks along the ceiling and wall to support the extension cord. The cord will run across the ceiling in such a way as to put no weight on the outlet, and then down the wall, so the charging cable that comes with the car is on the floor beginning where it plugs into the extension. Hooks would not work to support the original cable, because it is not long enough.

I know that's a lot of detail, but I want to describe all the steps, so they are all open to critique. What little thing won't work? what have I forgotten?

This was supposed to be easy, because before I bought the car, I was told the outlets were on the wall.

[RivkahChaya]

They simply fail because the designs were never intended or tested for the long, continuous power loads that a EV can draw while charging. The only extension cords I would trust are the ones I make by hand and test. ...If you have a question of safety, many here will be glad offer input.

It is my intention to buy from an electronics store, where I go for computer parts, and anything hard-to-find, or that really must work well. The buyers there know what they are doing-- they aren't just looking for the cheapest thing. And if I ask a floor person for advice, it's likely to be someone getting a degree in IT or physics. I'll pay more, but it'll be worth it.

[LeftieBiker]

Heat buildup usually occurs at the outlet, so having an extension cord plugged into the outlet, with the EVSE plugged into the other end of the cord, moves the temp sensor away from the outlet that it's supposed to be 'watching'. AFAIK, it's a kill-type setup, with the sensor cutting the connection if excessive heat is detected. I assume that it 'unbreaks' the connection when it cools, but don't know that for a fact.

[RivkahChaya]

Heat buildup usually occurs at the outlet, so having an extension cord plugged into the outlet, with the EVSE plugged into the other end of the cord, moves the temp sensor away from the outlet that it's supposed to be 'watching'.

OK. I misunderstood-- when you said "plug" I thought you meant the end that plugs into the car, and it was a feature designed to protect the car.

Hmmm. It did occur to me to get a surge-protector trip switch for the end at the outlet. I guess it should be heat sensitive too.

It's an unheated garage, FWIW, and temperatures are pretty low at night now-- it was 46F when I got up this morning. I know that's not helpful if it's vastly overheating because the system is overtaxed, but it shouldn't overheat from normal heat not being dispersed-- something that might have been an issue in July.

[knightmb]

From personal experience with a family member. Back in 2015, a family member bought a new 2015 Leaf. They only had the EVSE that the Leaf comes with (120V model) before I helped them install a 240V EVSE months later. While using the 120V EVSE, they had a garage with an outlet, external type since the garage had no walls. It was a two car garage and the outlet was just far away depending on which side you parked and which way the Leaf was facing, etc. They wanted to use an extension cord to make this easier for them when charging. I told them to get a heavy duty cord, don't cheap out, and check the plugs after a while to make sure they were not overheating. They went to the hardware store and bought an expensive, single outlet extension cord with 12 gauge wire. Should have been an easy, overkill setup that could easily handle 12A of power, no issues. One day I got a call and the outlet in the garage had melted, but apparently not enough to start a fire or trip the 15A breaker. The Leaf was charging over night and they didn't notice until morning when they tried to "move" the extension cord and it was welded into the outlet (but apparently still working). I later fixed the outlet by replacing it with a better quality outlet that could handle more power (20A version). I checked the extension cord (which I replaced the male end due to the damage) and what had happened was the "male" end had gotten dirty somehow, maybe someone dropped it in the floor and didn't think about it. But I could clearly see where the dirt had caused one of the contacts to be less than ideal and physics took care of the rest. The EVSE does have a thermistor in it for temperature overloads at the outlet, but when using an extension cord, you break this safety feature.

[RivkahChaya]

OK. Maybe I will use a multimeter to double-check the output of the outlet-- I mean, if for some reason it isn't performing up to what it should be, I should find that out.

I suppose I could request that the outlet be moved to the wall, as well. They'll probably say no, but it can't hurt to ask.

[Drew21]

1). You can offer to hire and pay a licensed electrician to move the outlet, thereby taking any risk/liability away from the garage owner. It's one thing to say "Hey landlord, do something for me" vs asking for permission to pay someone qualified to do the work.

2). The 120v EVSE that came with our 2014 Leaf is pretty long, with the heavy bit very near the wall plug. Is that how yours is? Our wall outlet is high enough that the weight of the EVSE hangs from the plug/outlet connection, which I didn't like. It took only a couple minutes to put hooks in the exposed studs and hang the heavy part of the EVSE on those hooks, thereby removing the weight from the outlet. I don't see why you couldn't do something similar on the ceiling.

I probably wouldn't worry about the light all that much (especially if it has a CFL or LED bulb). You surely turn it off when you're not in the garage, so the majority of the time when the Leaf is charging the light won't be on or drawing power.