Question about charging problems at a 120v outlet

[Stimyg]

I live in NYC and my parking garage kindly installed a 120 volt outlet for me. (I mainly use the car on the weekends so that's sufficient for me.) I've had a lot of problems charging here, as I outlined in another thread. Briefly, while the car begins charging at 12/12 amps, within a couple hours it usually lowers its charging rate to 5/5 amps, or more recently, just fails to charge altogether. (In case it matters, I'm monitoring the charge rates via the iphone App, since it's a parking garage and I live a few blocks away.)

I spoke to my local Tesla service center tonight, and the person I spoke to suggested that was probably a problem with the 120 outlet, and not the charging cable or car itself. He didn't say for certain but that was his guess. He's going to look at the logs. If that didn't show anything, they'd come get the car and test it. (His proposed way to test it was to pick the car up, and either test it by plugging it in at a 120volt outlet at the service station, or at his home, and then see how it charged. Which I thought was crazy, that that's the most sophisticated way to test the thing. I could do that myself for chrissake.)

So my question is: given everyone's experience, how likely is it that it's a problem with the 120 volt outlet / power supply itself, as opposed to the charging cable or car itself?

By way of explanation, if it IS a problem with the power supply the 120 volt outlet, it's going to create a lot of headaches for me, in that I then have to ask the parking garage to... I don't even know what. Install another one? What would I even do?

 

[brianman]

In your shoes, I would consider asking the parking garage for the contact information of the electricians that did the work. Then I'd connect those people with Tesla so that they can work it out together.

 

[Jason S]

Tesla testing it by plugging it in somewhere else, neutral 3rd party, makes perfect sense -- if it works somewhere else, then it must be the socket and not the cable plus car.

Prolly the 120 outlet is just installed with too small of cabling.

 

[FlasherZ]

So my question is: given everyone's experience, how likely is it that it's a problem with the 120 volt outlet / power supply itself, as opposed to the charging cable or car itself?

Unless your car shows an error that the charging cable isn't fully connected, it's likely a voltage drop problem. You may find that the car displays a message that it thinks it's attached to an extension cord (it won't display this on the app) when it uses reduced amperage.

It's likely that the run to the panel is very long and/or they used 14 gauge wire to provide the outlet to your space. Your remedy is to ask them to use 12-gauge wiring (or if a very long run, 10-gauge). They probably won't like having to re-run the cable, but it's the only thing that's going to work to get you the 12 amps.

 

[Cosmacelf]

Reduced amps in charging seem to often be caused by not having proper plug connections. Either the plug into the car isn't seated well enough (you really have to push it in well), or the plug into the wall socket is coming loose. Which given the weight of the UMC and big adapter head, isn't hard to believe. When you return to the car, does it look like the plug is still well plugged into the wall? What voltages are you getting when you first plug the charger into the car, before it ramps up amps. And what voltage are you getting after it has ramped up to 12 amps? And yes, the Tesla person is correct, the easier/best way to diagnose would be to find another plug somewhere and try it out.

 

[Stimyg]

I get decent voltage throughout - I've seen it anywhere from 115 volts - 122
volts, after it ramps up to 12 amps. Does that tell me anything about the outlet or line running to it?

Its possible the charger is not staying seated in the 120 socket well enough; the guys loop the UMC over the outlet which takes the wright off it, but still its not the tightest connection. It would take very little force to loosen it, amd even the little bit of weight that is on the plug at the outlet seems like it could do it? Anyone come up with any good solutions to this? I could put in a hook to hang it on, but even so I think I'd need a way to get it to sit tighter. Imagining a strap of some kind...? Hm.

Or it could not be that. This is the problem, there are a lot of possibilities, and its just a touchy situation since the garage is already going out of their way for me every time I pick up the car - their guys have to plug or unplug it, and think about whether its charging, whereas with a a normal car there's just turn the key. And I'm worried that if I put too much more on them they'll just say forget it, no EVs allowed, its not worth the hassle.

- - - Updated - - -

Meanwhile had anyone had similar problems with a 120 outlet? And if so what was the cause?

 

[Plug Me In]

I've charged on 120 just a few times and haven't had a problem like that. I would suggest though asking the garage if you could hire your own electrician to investigate and remedy once you've ruled out any issues with the car. I would think that would be fair and remove some of the burden from the garage.

 

[islandbayy]

I had this problem once. Remedy was that the plug was not completely in the socket. I had to use a rubber band to hold the plug into the socket. Then never a problem again.

 

[Tommy]

I am thinking the garage outlet may be a contractor grade rather than an industrial or hospital grade outlet. In other words, cheaply constructed causing poor contact with the Tesla plug. My suggestion would be to take the Tesla adapter plug to one of the big box stores or an electrical supply house as they will have an assortment of high quality industrial and hospital grade plugs. The purpose of bringing the adapter is to find the brand/outlet that really secures the plug.

Hopefully, you can replace the outlet or if need be hire an electrician to install the new outlet. My suggestion is all predicated on you already confirming the fault doesn't lie with Tesla, and as previously stated you should be able to determine that by plugging into a different outlet offsite from the garage outlet and seeing if the problem still persists.

 

[Cosmacelf]

Here in CA you can buy tamper and weather resistant receptacles. They are a $&@! To plug in and out of, but they hold the plug very securely. Also, ideally the receptacle should be 20a rated ( assuming they used 12 gauge wire), so that would be a receptacle that has the horizontal notch in the left blade. If it were me, I'd just buy a new receptacle after testing the fit like Tommy suggested and replace it. But have you tried testing it on a different receptacle yet??

 

[FlasherZ]

I get decent voltage throughout - I've seen it anywhere from 115 volts - 122
volts, after it ramps up to 12 amps. Does that tell me anything about the outlet or line running to it?

It really doesn't tell me too much, although generally you can infer that if you see 122V, it's not a very long run. The most important element, though, is the voltage drop -- look at the voltage when you first plug it in, when it says "0/12" and then look at it when it ramps up to 12 amps, and compute the difference. That will tell you a lot about the circuit it's on.

I wouldn't jump to conclusions about replacing outlets, etc. yet: the car can't tell if the plug is loose, or the receptacle is contractor grade, or whatever. It's reducing charge based on some factor it can detect and you should know that before you take action. There are two known factors that cause the car to reduce its charging power -- voltage flakiness / drop (when the car thinks it's on an extension cord), and high heat, the result of needing battery cooling, sun shining on the UMC, or the adapter being loose and generating high heat (although the 14-50 adapter melting cases didn't seem to generate enough heat in the wires to affect the UMC).

If the car is only charging at 5A, it's worthwhile to make the walk down there to feel the UMC and its cords, look for car errors (the "extension cord" warning, etc.)

Tesla can also tell you why the car reduced its charging power, whether based on seeing a pilot signal change (meaning the UMC thinks something's wrong/hot/etc.) or the car's decision to draw less (meaning the battery pack needs to be cooled, voltage drop is too high, power is too flaky, etc.)

 

[qwk]

Having charged on 120V quite a bit myself at dozens of different outlets, I would say that this problem is most likely with the outlet/wiring in the garage. When a UMC goes bad, it just stops working all together or melts. The easiest way to troubleshoot this would be to try another 120V outlet or two and go from there. Unfortunately shoddy electrical work is pretty common, so it wouldn't surprise me that the electricians used subpar parts/too thin of wire.

 

[Stimyg]

It really doesn't tell me too much, although generally you can infer that if you see 122V, it's not a very long run. The most important element, though, is the voltage drop -- look at the voltage when you first plug it in, when it says "0/12" and then look at it when it ramps up to 12 amps, and compute the difference. That will tell you a lot about the circuit it's on.

It's about 120-122 volts before it ramps up to 12 amps; after it ramps up it's anywhere from 115-119, usually on the higher end. How's that?

 

[FlasherZ]

It's about 120-122 volts before it ramps up to 12 amps; after it ramps up it's anywhere from 115-119, usually on the higher end. How's that?

That's not bad at all - less than 5%, and that shouldn't trigger the car's extension cord warning.

I think you're going to have to ask Tesla why it's dropping the charge current, they should have something in the logs or at least the next clue. It could be some type of a loose connection creating an unstable voltage somewhere, but you're not going to know that unless they can tell you that. Any action you take is likely going to be shotgun troubleshooting until you have that.

 

[Stimyg]

Thanks for your suggestions. There's a lot to consider here. I'm definitely wondering about the outlet connection since it doesn't seem too secure a connection to me, and the outlet is 4' off the ground, meaning you have to loop the UMC over the outlet (which projects out from the wall) to take the pressure off the plug, so it's all a bit precarious. It also seems the easiest thing to address by myself. I could try a rubber band-type solution. Here's another thought, tell me if I'm crazy: if I were to take a very short (say 6'), high-gauge (say 10 or 12 awg) extension cord, I could plug that into the outlet, secure it nice and tight with duct tape if need be, then the actual connection to the UMC would into the female end of the extension cord which would just by laying on the parking garage floor, and thus would be completely supported and not nearly as likely to pull out. Thoughts?

 

[NotMandatory]

I can't speak to any of the possible explanations for the observed behavior, but I can tell you that we had our 85 MS for almost 3 weeks before we finally had our new 50 amp circuit installed in the garage. During the 2-3 weeks prior, we plugged it in every night using the standard 120v/15a circuit available in our garage...and never had any issues with charging. (It would always draw the full 12a current available.)

 

[Cosmacelf]

Yes, a 10-15' 10 or 12 gauge extension cord, well secured would be a good test and maybe a simple solution.

 

[Stimyg]

I was having trouble finding a short 12 gauge extension cord with a standard 120v plug. So instead I got a 9' 14 gauge, rated up to 1875 watts. (Also got a 3' one in case that fits better.) Is that OK to use to test it out? How about on a permanent basis?

 

[FlasherZ]

I was having trouble finding a short 12 gauge extension cord with a standard 120v plug. So instead I got a 9' 14 gauge, rated up to 1875 watts. (Also got a 3' one in case that fits better.) Is that OK to use to test it out? How about on a permanent basis?

It should be ok to test, and it's rated for 15A, so you should be ok at the 12A charge rate.

Just a simple word that most on the forum have seen before -- Tesla says no extension cords, and NEC requires you to follow manufacturer's instructions or you're violating code, so it may have insurance or other legal implications for you. Just be aware.

 

[montgom626]

By way of explanation, if it IS a problem with the power supply the 120 volt outlet, it's going to create a lot of headaches for me, in that I then have to ask the parking garage to... I don't even know what. Install another one? What would I even do?

I charge exclusively on 120 V with no problems at all. Have a electrician fix that outlet.