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Charging randomly stops - 236v the culprit?

Discussion in 'Model S: Battery & Charging' started by drewnick, Aug 5, 2014.

  1. drewnick

    drewnick Member

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    Just drove 1,000 miles on SCs and municipal chargers with no issues, also have a NEMA 14-50 charger @ home that worked great the first 3 times I've used it.

    Now I'm at my parents' house where I had a 14-50 installed at the outside panel. When I plug in it starts charging and in fact got about 180 miles but then randomly stopped. No messages on the screen, no nothing. Just stopped charging.

    Starting charging back from the app does not work. I had to pull the plug out physically, then insert again. I noticed that the voltage starts at 242 volt but drops to 234-236v as soon as amps start increasing. The car limited itself to 30A of 40A already, and keeps stopping now after just adding milage for maybe 30-60 minutes. I've just tried limiting it to 24A to see if this will at least get us charged, but really I need to be able to get 40/40A on this plug for our trips to be comfortable.

    Any ideas? Call power company? Electrician?
     
  2. Lloyd

    Lloyd Active Member

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    You have a 5% drop already at 30 amps. I suspect that something else kicked on in the house, water heater, air conditioner, oven etc. that caused an additional drop. 24A will charge your car from empty to full range charge in about 14 hours. First check the wire gage at the 14-50 install, then the capacity for the house. If you have 100 amp service and running car, and normal house use you may be taxing the feed to the house. We have seen others with outdated and insufficient feeds to meet their panel's rating.
     
  3. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    When it stopped, what was the behavior of the car? Even when charging completes, the car displays "charging complete" on the screen when it completes a charge. Does it say "charge port open"? What was the color of the LED ring around the connector when the car is unlocked? What did the battery screen display for voltage / pilot current?

    If you use VisibleTesla or the app, what does it show? Does it offer an option to "start charging", or "open charge port"?

    These answers can help us track something down. I suspect you may have a faulty charge port but that's based on what little information we have.
     
  4. NigelM

    NigelM Recovering Member

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    Call your local service center first (i.e. call Alberto) and have them check the logs. If it's something on the car they'll tell you; don't waste money on an electrician until you know there's a house issue. BTW, fluctuations around the levels you indicated are pretty normal and shouldn't bother the car.
     
  5. bonnie

    bonnie Oil is for sissies.

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    +1 ... as usual.
     
  6. youlikeadajuice

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    I've recently had similar issues, however I've gotten a red ring on the charge port and seen my voltage on the electric meter read as low as 225v. I checked with Tesla, and they indicated it was probably an issue with my electrical supply/wiring (yours might be different). I had a dedicated feed set up for my detached garage (meter, 100 amp service, nema 14-50) and the car is the only thing on it. I'm going to give the power company a call first since the meter voltage is so low...it fluctuates between 238 and as low as 225 during charging recently. I've had the car about 18 months, it just started doing this recently.
     
  7. mmh

    mmh Member

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    I wouldn't blame the voltage drop without asking Tesla first. Mine commonly charges at [email protected] as seen below. However this is through the HPWC and not a 14-50, so maybe the S is less sensitive to it.

    5986_Charge_Speed_CLSSs.jpg
     
  8. kota23

    kota23 Member

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    If the car is limiting amps to 30, then there is a problem with wiring I would assume. Voltage below 240v doesn't matter as the charger will automatically adjust for that. Most commercial sites you usually only get 200v since they are set up as 208/110 versus a 240/120 setup that you see in residential. Have the electrician back out who installed it to take look and verify phase to ground, phase to phase voltages and also check for loose connections. If you are charging at other 14-50 sites and public charger without issue then it is something with that specific installation at your parents house.
     
  9. Lloyd

    Lloyd Active Member

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    It's not the low voltage, its the drop from the initialization of charging.
     
  10. drewnick

    drewnick Member

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    Wow, thanks for all of the information guys. Tesla SC called this morning and said the logs are indicating it may be an issue with the charger.

    Last night I dropped amps to 24/30 (should be 40/40 if all is perfect on a 14-50) and it worked all night. Since we are about 650 miles from home, this was critical to get us home, where Tesla will pick it up.

    I'll come back and update the thread. Good to know a voltage drop is not necessarily an issue. I have seen ~200 volts in the muni garages in South Carolina so obviously, as mentioned, the car adjusts for that.

    The behavior seemed erratic but basically it was not charging, and would not start back. One time the UMC was green the next the UMC was red. We'll see what they say.
     
  11. youlikeadajuice

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    This is what I suspect as well, but is it acceptable for the power company to allow such a large drop (238v down to 225 or less)? I don't think my particular problem is with the wiring after the meter since the meter itself is showing the lower voltages.
     
  12. Lloyd

    Lloyd Active Member

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    5% is ok and I don't see problems with this level of drop, but I do see problems with charging when the voltage drop is 10% or more. Thus my comment that if something else kicked on inside your house to make the voltage drop more severe, it could cause the car to halt the charging process. If the Meter is showing the lower voltage, then the feed to your house could be on the light side.

    See if it continues with the new HPC. If it does, then call the power company with the car there ready to charge when they arrive.
     
  13. techmaven

    techmaven Active Member

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    This.

    I've been to a J1772 that started at 202v, and then held 200v @ 30A as the charge ramped. But if you start at 242v and then drop like that, then the car will hold back as it should. Sometimes I plug into a dodgy 120v @ my parents and I have to charge no higher than 7A as it holds 109v.

    My issue with Tesla's algorithm is that it isn't as stubborn at maintaining a very low charge rate and instead, just gives up. Why not stubbornly charge at 16A or whatever that will hold voltage and send a notification via the phone app? That's better than waking up with no charging at all. And if it won't charge even at 16A, then that should be clear enough from the get go while the owner is still near the car.
     
  14. youlikeadajuice

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    You may not see a problem with it, but my car certainly does considering it stops charging with that kind of drop :) The car is on a completely separate line and meter from the house (detached garage and nothing else shares the 100 amp service in the garage with the car)...so if something in the house is kicking on and tripping the car, my thought is that the transformer can't handle the power that is being drawn. There are multiple houses on that transformer, so it could be anybody on my small street with something kicking on that is causing the voltage drop. It seems the drop is worse on hot days (people running lots of air conditioning), so I have no doubt there is additional strain on feed, but I did not have these problems last summer. I always used to get strong voltage, 235 or higher...something is different or maybe the car is more sensitive now with newer firmware, either way, I have a problem charging at 40 amps now :(
    .
     
  15. Lloyd

    Lloyd Active Member

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    You said it stopped in the middle of the night, thus my comment that something else is comming on to create a larger drop and interfere with your charging. Just my theory.
     
  16. Forty Creek

    Forty Creek Member

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    I too continue to have a problem with the charge drop down. HPWC is on a separate 100 amp breaker inside a 200 amp panel. Trying to charge at 80 amps, the car almost always drops to 59 amps. Sometimes within a few minutes and sometimes after 30 minutes. This happens even with scheduled 2:00 AM charging. The voltage starts at 243 and eventually hovers around 226 or so (looking at VT on my laptop). A while back, I called the local utility about it and unfortunately they came when I wasn't home with the car. They said everything checked out, but of course that was without an 80 amp continuous draw. So far it hasn't been an inconvenience, but it bothers me that there IS something wrong. Either the HPWC, the car, my wiring or the power from the street. Tough to diagnose for sure.
     
  17. youlikeadajuice

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    Yes! This is my problem except I just have the regular UMC. Can't charge at 40 amps, but 30 seems to be ok. I'm also glad I am still able to charge, but agree it's frustrating knowing there is something wrong preventing me from getting the full 40 amps. I just spoke with my utility today. They went and checked things out and said they made some slight adjustments at their substation and it should bump my voltage up. I'll try tonight when I get home.
     
  18. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    #18 Cottonwood, Aug 6, 2014
    Last edited: Aug 6, 2014
    17 Volts drop, starting at 243 is a big drop, 7%. I assume that Voltage drop is with 60 Amps. That is 17 Volts times 60 Amps or a kiloWatt of power heating things up somewhere; assuming a resistive loss, that would be 1,800 Watts at 80 Amps! If I were a Model S, I would fold the current back to 60 Amps for safety, and maybe more. If I were you, I would set the MS to charge at no more than 40 Amps until the problem is fixed, or you at least determine that the problem is outside your house. You need to figure out this problem, by yourself, with an electrician, or with the power company.

    You can take a shotgun approach and start feeling for hot spots. You are not looking for warm cables. With this amount of power, there is likely to be a place that is "burn your fingers" hot.

    Another approach is to start mapping the Voltage drops from the transformer to your car. It's good to see what the Voltage is on the 240 lines at your circuit breaker box. If comfortable and you know what you are doing, you can check this by taking the cover panel off of the breaker box and measuring the Voltage with and without the car charging. Another good way to measure this is to check the Voltage at another unused 240 Volt outlet; think about unplugging the electric dryer or range. If most of the Voltage drop is at your breaker panel (or other, unloaded 240V outlet), then the problem is probably undersized wiring to your house or an undersized transformer; time to talk to the power company. If is not much Voltage drop at the panel, then most of the drop is between the breaker panel and your car, time to call your electrician to find out where the loss is, probably undersized wire or poor connections.

    Good Luck!
     
  19. brianman

    brianman Burrito Founder

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    Maybe someone near Forty Creek has one of the temperature guns/cameras. Better than burning your hands. :)
     
  20. Forty Creek

    Forty Creek Member

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    Thanks for the suggestions Cottonwood. I'll work away at this until it's resolved.

    - - - Updated - - -

    Another good idea. I'll ask around about the temperature gun. All of the wire is in conduit but the conduit is out in the open. If there is a hot spot, it would probably be evident. Thanks.
     

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