What have I missed? (regarding charging EV at home)

Factual Questions
1

I am the proud new owner of a CR recommended, fully electric, Nissan Leaf. It is a pleasure to drive, and has the exact amount of “stuff” I’m comfortable with.

I live in an apartment building, but it rents out garages for quite a bit less than 1/3 of what I was spending on gas a month (long, boring story). The garages each come with a standard 120v/3 outlet, so I rented one. They charge slowly, but still should charge the car from ~50% to 100% overnight.

Turns out the outlet is in the ceiling.

This is a problem, because when connected with the standard plug adapter, the charger is way too heavy, and also must drape over the car. After a couple of hours, it is going to fall out, and damage the roof or the windshield, assuming it falls quickly, and not slowly, causing an arc that sets the building on fire.

So, I buy an extension cord, and hooks (with landlord’s permission), and am ready to string the cord (12/3, outdoor use, can handle the amp the cable will draw), so the connection to the cable that came with the car will connect at the floor.

Then, someone tells me the original adapter has a heat sensor that automatically shuts everything down if it detects overheating at the outlet. The extension cord defeats this feature.

Hmmmm…

OK, I find a short cord to put between the extension and the outlet that has a breaker, and will trip if the outlet overheats (or surges). It is also `12/3, outdoor insulated.

So, outlet → breaker cord → extension cord → charging cord with adapter that came with car → car

Am I missing anything?

2

The outlet will overheat if there is a bad connection. I had this happen with a Tesla with 240V 40A - the outlet was visibly charred by one prong - be sure the screws connecting the feed wire to the outlet are TIGHT! This will of course require a stepladder and turning off outlet breaker, taking off the faceplate, taking out the outlet to be sure. I also had a house once where the main breaker popped erratically - turns out over time, copper will deform; the main feed wire was physically loose. The older the outlet, the more reason to check.

If you have an extension or plug that can do the same trick as the charger plug - good. I assume Nissan’s charger does the heat detection function because not everyone checks the outlet connections when they are essentially doing the equivalent of running a toaster out of a plug for 8 hours (1200W 120V)

As usual, the shorter the overall cabling the better.

3

I charged my Tesla with a 120v outlet in the ceiling for quite a few months. Worked fine. It was the outlet for the garage door opener, as it happens.

A 12/3 extension cord should be fine, but can you get away without it? My Tesla mobile charger cable was about 20 feet long. It also had a fairly heavy brick, but with a few eyehooks, I could suspend it without having any extra load on the outlet (aside from the weight of the pigtail). The rest of the cable went over to being just above the charge port for the car, and then hung vertically. I had a little plastic thing on the wall to hold the plug when not in use.

That would be ideal, if the geometry permits it. If you must use an extension cord, it should be fine, but I would try charging for a couple of hours, and then grab various points with your hand to see if anything is too hot. Fairly warm is ok. Hot, and especially anything painfully hot, is not.

To be honest, I’ve never heard of a breaker cord before. It shouldn’t be necessary. The circuit itself has a breaker that will trip if the current limit is exceeded. As long as everything has been installed correctly. But things are less likely to go wrong at 120v/12A than 240v/40A.

4

You can go with just the extension cord. Infact it is against fire code to plug an extension cord into a another cord.

If you are worried about the outlet there is a simple test. If your extension cord has more than one outlet on it, plug the extension cord in plug the charging cord in but donot turn on charging. Then using a volt meter take a volt reading at the extension cord. It should be between 110 and 120 volts AC. No stgart charging the car and not the voltage. If it has not droped over 2 or 3 volts the you should be ok. You can come back a few hours later and take another reading while the care is charging. If you get a large volt drop then the outlet may have a bad connection or there is a bad splice somewhere in the wiring run.
Also if the outlet is not on a dedicated circuit (only one outlet on the circuit) then if enough people charge their cars at the same time the breaker will trip.

5

Of course, one option would be to swap the outlet out for a twist lock unit and purchase (or construct) an appropriate extension cord. Not only will the plug remain secured, but the twist lock plug and receptacle will have a much larger contact area for the current.

Don’t know if the landlord would allow this, but it’s a cheap, easy job for an electrician and can easily be reversed when you move. Compared to the cost of renting the garage and buying the car, it’s a rounding error.

The idea of plugging one extension cord into another is not optimal, though I doubt you would ever have any problems. Fire marshals often look for this during inspections and will sometimes cite it.

6

Another handy hint from days of yore - take an AM radio and wave it near the outlet while charging. If the closer to the outlet you get, the more static, then you have a loose connection (probably screws inside the outlet need tightening). The fun part of this is trying to find a portable AM radio nowadays.

7

I would think suspending the charger like this would work well. You could even do something to help support the cord near the plug to really be sure nothing would be pulling the cord out. If this is your cord, it looks like the charger has holes on the corners

For heat dissipation, I would recommend stringing it up from the top two holes so that it hangs vertically. That will make it so that air can flow all around it. I would recommend getting two short bungie cords and looping their hooks at the end of the cord into the two holes. Then mount the other ends of the bungie cords to the ceiling. The stretchy bungie cords will allow a small tug to stretch the cord rather than pulling the cord off of the ceiling.

8

I think I also should have asked if the OP has looked at the instructions provided with the charger. If it states that you should not use the charger with an extension cord, then there is a problem. All listed equipment must be installed and used in accordance with the manufacturer’s instructions. (This is a fundamental of the NEC, though I don’t know exactly what codes are applicable in your jurisdiction.)

Using any type of extension cord, even very high quality units, is always a compromise.

9

One other thing to keep in mind is that any hooks you install in the ceiling should either be screwed into a stud or into a drywall anchor. I’m not sure how much experience you have with drywall, but it’s basically just chalk. If you screw a hook into it, it will easily get pulled out.

10

EVSEs (what people incorrectly refer to as “chargers” - the actual charger is in the car) should not produce any heat that needs to be dissipated. They’re just a box containing a contactor (relay) for the power, a GFCI to open the circuit in the event of a ground fault, and a tiny microcontroller to tell the car what size circuit it’s connected to. None of these generate any appreciable amount of heat.

11

Yes, the heat danger is the amount of current flowing. Imagine running a toaster for 8 hours, consider what the cord must be putting up with. Most chargers are heavy-duty wires, but any loose contacts are the weak spot - wires not screwed down, plug not fully in, etc. I assume the risk at the plug - “the weakest link” is why the charger/EVSE is equipped with a sensor to detect anomolous heat.

For simplicity, I would do as suggested above. Hang the unit from the ceiling, with hooks so the cable hangs down where the charge port will end up when parked. Most units will have enough cable to accomodate this. I assume “outlet on the ceiling” means it is positioned for a garage door opener? Thus should be centered over the car or between where two cars would park.

12

Dimension-wise, that’s pretty close to the Tesla charger. As others said, heat dissipation shouldn’t be a problem since the box doesn’t do that much. It shouldn’t be wrapped up in a blanket or anything, but it would be fine up against a wall.

Eliminating the strain on the cable is the main thing. Two hooks spaced where the cables exit the box (ideally so they grab the rubber strain relief molding), and then several more to bring the cable to where it’s needed. The pigtail can be bent, but ideally not so much that it’s putting force on the outlet trying to spring back.

13

Yeah, I do, plenty. The garage is plywood walls and exposed studs. No drywall. Just going to screw into the studs.

14

Yeah-- I considered just trying to suspend the actual plug over the car, but it doesn’t reach unless I park the car so there’s only about 2 inches clearance between the backend and the wall, and there might be some strain on it.

Absolutely no strain with a 15ft cord.

The overhead end, with the adapter is heavy enough to damage the car, and so is the panel that shows charging details, which will also be suspended in a way where it can fall and damage the car, or hang, and strain the cord.

There’s just no good configuration without an extension cord.

15

I’m still a little confused at your description. In the OP, you mentioned that the extension cord would run all the way down to the floor. And then the charge cable would connect there and presumably run some distance away.

But there’s no need to go all the way to the floor–that’s going down a few feet and then up again for no reason. If you keep it suspended, with the plug part dangling from the ceiling and only long enough to reach the car, then you could save 5 feet at least, and possibly more. If you must use an extension cable, try to keep it as short as possible.

16

That of course, varies by jurisdiction.

One way to make sure the extension cord doesnt overheat is to get a heavy duty one.

17

I’ve got the heaviest duty ones possible, for 120 outlets.

18

The violation is against the NFC (national fire code) which to my knowledge every state has adapted.

19

Technically it’s also a violation of the NEC (National Electrical Code) in the US to permanently install an extension cord by attaching it to the building:

(2008 edition quoted; sections may have been re-numbered in later editions but the rule certainly hasn’t gone away)

20

Nissan’s website says that Level 1 (120v) charging adds “approximately 2 to 5 miles to your LEAF’s driving range every hour.” At the high end of this range, a 12-hour overnight charge would add 60 miles of range - so about 25 to 40% of full charge (depending on your battery option). At the middle of this range, it would be about 42 miles of range, so 18 to 30% of full charge.

To do this, the charger would be drawing around 12 amps / 1500 watts, so 18 kwh a night / 540 kwh per month. At $0.20 per kwh (about the US average), that’s just over $100 per month of electricity. (Actual amount will of course depend on how much you actually drive.)

And to draw that much power, you’ll need almost exclusive use of one 15-amp circuit - if any other outlets are on the same circuit breaker, they must support no more than small loads (say, a couple of LED lightbulbs) or the breaker will trip.