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Charging issue

Discussion in 'Model S: Battery & Charging' started by Rbcnr, Apr 18, 2017.

  1. Rbcnr

    Rbcnr Member

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    New owner here. I am having difficulty with charging (nema 1450) my MS. Basically if I come home at say 8 pm and immediately charge the car, it will charge normally at 26-29 mph , 215 v, 40/40 a (successful like 80% of the time and 20% the latter happens). If i connect the charger but set the car to start charging later, say 11 pm, half the time it will say charger unlatched or limited charging at 11 mph.

    I put the charger in the car and in the outlet correctly. Doesnt seem tricky. Sometimes re-attaching it will fix it and otherwise it stays at 11 mph. M

    Anyone else experience this or know how I can fix it? Am I doing something wrong? Thank you in advance.
     
  2. JHuberman

    JHuberman Member

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    The charger evaluates the line and if it detects any problems it slows down. You should check that the outlet is in good condition and that there are no loose or corroded connections in the outlet box, any intermediate connections, or the panel.
     
    • Helpful x 1
  3. Rbcnr

    Rbcnr Member

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    It was newly installed and in great condition. I forgot, I actually mentioned this problem to the electrician and he said he has heard this before but doesn't know why...and to check with Tesla. Car is going to the SC soon for some other things, so will have them check it out. Thanks
     
    • Love x 1
  4. Lloyd

    Lloyd Well-Known Member

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    You might want to check your installation of your plug for under sized or improperly terminated wires. Voltage sag to 215 from 240 is a lot. It may be that the car is decreasing the charge rate to protect you!
     
  5. David99

    David99 Active Member

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    Just speculation, but maybe at 11 pm there are other things in your house or in your neigborhood) that draw a lot of power. Tesla checks the voltage drop and reduced charge power if it detects that the grid is under a lot of load or the voltage drop is more than normal, or other things. No one really knows what the UMC or HPWC is looking for when checking the grid but Tesla seems to be on the careful side.
     
  6. Rbcnr

    Rbcnr Member

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    Appreciate the input. So today the same thing happened. Got home at 7 pm. Set to charge at 9 pm. Saw that it was 11 mph. Went outside, unlocked car, took charger out, locked car, inserted charger -> green light ring and started charging at 26 mph. In retrospect I think the yellow light ring was there at 7 pm. Maybe I didn't insert it completely? I feel like I insert it pretty well (haha what am I saying). I mean do you guys jam it in there? I dont want to break anything. Thanks
     
  7. Lloyd

    Lloyd Well-Known Member

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    Your initial post indicating 215v is telling! Check your electrical supply!
     
  8. Rbcnr

    Rbcnr Member

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    I am embarrassed to say I have not learned so much about the inner workings of the car. Slowly reading and learning all the info about the car. What exactly do you mean? I've heard a few people here in NY mention they get numbers like 27-29mph, 218-220 and 40/40.
     
  9. BerTX

    BerTX Active Member

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    I think maybe that was mis-reported. Wouldn't have been getting 29 MPH at 40 A and 215v.

    OP, I think it is the plug insertion. Practice doing it a few times. You might try inserting the plug first, verifying the charging, then stop the charge and set the timer. Once you have confidence that you are getting a good connection, you can go back to just plugging it in and forgetting it.
     
  10. Rbcnr

    Rbcnr Member

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    I think you are right. Sorry, I probably messed up the numbers (as I was using memory, didn't make a log but should have). I am starting to think its plug insertion too. So if I set to charge later, after I connect, it should be blue correct? Or I guess like you said I can start the charge, get a green ring, then stop and set timer (more steps). Thanks everyone for your prompt input.
     
  11. Lloyd

    Lloyd Well-Known Member

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    If you started with a 240v circuit, voltage is lost over a line when load is applied. More voltage will be lost if the line is too long, or the wire or connection is inadequate. 215 volts from an original 240 is too much and if that is correct, the car is decreasing the charge rate to prevent overheating in the circuit and if not corrected a potential fire.

    Check your numbers and repost!
     
  12. JClu

    JClu Member

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    Yellow light means the cars thinks the connection was not properly aligned and therefore would charge at reduced rate.

    Correct. I think if you see the blue light, the car should charge at the highest rate you set it at (40 or 48A). You shouldn't have to do the extra steps you mentioned later.
     
  13. Blup85

    Blup85 Member

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    i have my own transformer at my home and when my solar is cranking out 10kw, I get 256v @ 40amps and see 31 mph charge rates with almost no voltage drop (maybe 1-2volts?) When I charge at our cabin, I have an initial voltage of 220-223v, and it drops down to 211-214 (due to old wiring, shared transformer with a lot of homes and a long run) and my charger lowers the charging speed almost all the time. I plan to fix the long run wiring issue at the cabin, not much I can do about the transformer unless I get some movement from my utility, but until then I just sent the amperage to 20 to be safe. From what I've experienced, depending on your initial voltage, it seems like anything more than 3-4% voltage sag causes a lowered amperage (starting @ 240v, after load is engaged voltage drops to ~231ish..?)
    Sounds like you need an electrician.
     
  14. brucet999

    brucet999 Active Member

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    How does the on board charger know if you have a voltage sag when it sees less than 240V? The thing will charge just fine at 208V 40A from a HPWC off one leg of three-phase power. How would it know whether OP's 215V is what the poco supplies or big loss from his panel?
     
  15. Blup85

    Blup85 Member

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    Thats why I am guessing it measures the "initial" voltage, then once the charger actually starts drawing a load and sees more than a 3-4% drop, its lowers the amperage automatically? Like you mention, it works fine for 208, so 3-4% except-able voltage drop would be 4-5 volts (or 203v?). Of course I'm just guessing from what I've experienced. Someone else might have a better idea.
     
  16. Lloyd

    Lloyd Well-Known Member

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    It knows what you start at AND what you sag to under load and reacts accordingly!
     
  17. brkaus

    brkaus Active Member

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    It is watching the initial condition as it ramps the current. I haven't figured out the exact %, but see it frequently at ChargePoint locations.

    Park the car at your charging location.

    Set the charge current to minimum.

    Plug in and start charging.

    Watch and record the voltage as it ramps up.

    Once stabilizes, continue to increase the amps on the central screen and record the voltage for various amp settings.

    Report back.
     
  18. brucet999

    brucet999 Active Member

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    So, at home I charge routinely, according to my display and my Tesla app, at 237V, 24A/24A. Volt meter displays 240V between terminals on my panel and at the 10-30 outlet. Are you saying that If I could watch the car's display at the moment I plugin, it would momentarily show the no-load value of 240V for the few seconds before charging actually commences, then drop to 237V under load, and the system remembers that momentary no-load value, comparing it to the voltage under load throughout the charging process?
     
  19. Lloyd

    Lloyd Well-Known Member

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