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Is this normal for home charging?

Discussion in 'Canada' started by hingisfan, Jan 30, 2015.

  1. hingisfan

    hingisfan hingisfan_Mark_V

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    Just got my home nema 14-50 setup last night. Plugged in with only about 10% battery left and got 40/40 amps very quickly. Just plugged in now with about 60% battery and I'm getting 229V 30/40amps. Haven't seen it go above 30 yet at all. Is this normal or is there an issue. Car is cold, has been parked outside for 4 hours.
    Thanks!
     
  2. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    It sounds normal to me. There are several things that could be going on here:

    1. Battery heating.
    2. Check that the amps are still set to 40--if the power fluctuates, the car will lower the amps to 30 to protect the house wiring.
    3. Cold batteries will cause the car to charge more slowly.
     
  3. hingisfan

    hingisfan hingisfan_Mark_V

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    OK thanks...just making sure its all good.
     
  4. CHG-ON

    CHG-ON Still in love after all these miles

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    Also, though it shouldn't happen at 60% SOC, as the battery fills, it will automatically reduce the amps in order to not stress the battery. I am not positive, but I believe the taper begins at 85%. The batteries charge much more quickly when at low SOC and that is normal.

    Isn't it great to "fill up" your car in your own garage?!
     
  5. hingisfan

    hingisfan hingisfan_Mark_V

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    Yes, its great to not have to think about range on day to day driving. I only had to for 2 days but that was enough. i almost bought a Leaf and then a Kia Soul EV and I can't imagine going through that on a daily basis. Also, while it's great that hotels, etc offer L2 charging, it is really quite slow when you actually have to sit there and wait. Supercharging while on the road and L2 at home while sleeping is the perfect setup.
     
  6. andyro

    andyro Member

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    As Jerry33 said, but I had major problems with voltage fluctuations and charging stepping down to 30amps constantly - the telltale sign of voltage fluctuations (really not a big deal - just slow) is you'll get a 'bad wiring or extension cord used' warning. Getting a HPWC instead fixed this (esp. for cold outdoor locations, ie. -30C)
     
  7. Steph_S

    Steph_S CAN #312 VIN P06173

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    #7 Steph_S, Jan 30, 2015
    Last edited: Jan 30, 2015
    No, it's not normal. You should be at 39 or 40 amps. A bad wireing error has occurred. Unplug and plug back in. Dial up the car to 40A. If it falls back to 30, you should check your installation. Your wire gauge is maybe too small or there might be a screw loose somewhere. Make sure the screws are extremely tight on the breaker and the 14-50.

    You won't see any taper until the car is 95%+ full on the UMC with a 14-50. The battery should be warm enough to hold a steady 40A after at most 30 min even at -30C.
     
  8. hingisfan

    hingisfan hingisfan_Mark_V

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    I'm running #6 so the wire should be more than enough. I'll have to get my guy to come back and check if this is an ongoing thing. Like I said, last night I had 40 amps no problem, but tonight it's been exactly 30 the whole time.
     
  9. Steph_S

    Steph_S CAN #312 VIN P06173

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    Unplug and replug your UMC. Then manually increase the amperage to 40A. If it drops back to 30A, then you have some sort of problem and should get it checked out.

    #6 should be sufficient for most installations ( it's what I have)

    Once set to 30a at a location, the car will stick to 30A, unless you manually increase it back to 40.
     
  10. roblab

    roblab Active Member

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    I am having the same problems. I took my charge cord to Tesla to have them check it. All was fine. Have re-tightened all screws. Still the car jumps down to 30 amps pretty quickly and posts an error on the dash. Once it said I should replace my "extension cord"!!!

    I have had this happen at my brother's house once. It was the breaker. That's my next step. New breaker.

    I can't imagine how it could be the #6 wire. The outlet should be good. I never feel any heat anywhere. Breaker, or outlet?

    I can't figure this out yet, but I will post whatever my problem solve might be. I would guess that with Tesla's more delicate charging software, trying to prevent any "house" f***s, this will get more common.

    If I had more than a 100 amp sub panel, I would consider trying to install an HPWC.
     
  11. mibaro2

    mibaro2 Member

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    you could try charging at one of the faster suncountry chargers. If it goes at or above 40a there, then you know it is your wiring or umc. If it doesn,t go above 40a, then it is the car.

    I use a 14-50 at my house, and it stays at 40a right from when Istart charging to when there are 10 km left (95%).
     
  12. wayner

    wayner Active Member

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    I would say the perfect setup is a HPWC at home.
     
  13. wk057

    wk057 Senior Tinkerer

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    Generally when the car reduces power to 30A from 40A the home wiring is insufficient for the task. If the car senses a voltage drop above a certain percentage it will reduce power to protect the wiring. The more of a voltage drop the more heat is generated in the wiring in the house and the more of a hazard it becomes. Higher current draws cause a larger voltage drop on insufficient wiring.

    Sometimes other loads in the house can kick on during charging (HVAC, electric range, dryer, etc) and cause the voltage to sag as well since the main feed wiring may be insufficient for the task.

    Take a peak at what the voltage shows in the car before it starts drawing power, and take a note of what it is. Then see what it shows at 40A. I bet you're seeing significant sag.
     
  14. hingisfan

    hingisfan hingisfan_Mark_V

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    I'll check tonight....last night I was at 229V at 30 amps tho.
     
  15. Pricee2

    Pricee2 Member

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    That seems a little low to me. I run between 237V and 240V at 40 amps.
    Main line varies between 238V and 242V.
     
  16. Canuck

    Canuck Active Member

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    I've had this happen at my cabin when plugged into my range outlet using an extension cord. Sometimes the car senses trouble and reduces the amps but it always tells me that it has done that with a warning in the dash. Are you seeing any warnings?
     
  17. wk057

    wk057 Senior Tinkerer

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    229 is pretty low at 30A. Service is supposed to be 240V. So, that would be a ~5% drop right there at 30A, likely more at 40A.

    For comparison, I only lose at most 5-6V at 80A with my HPWC.
     
  18. hingisfan

    hingisfan hingisfan_Mark_V

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    No warnings....my wire run is pretty long tho, about 90 feet, and I am using two wires connected in a junction box, but they are both #6, which should be more than enough. The only other thing I can think of is that it was too cold for my heat pump to run last night so the backup electric furnace kicked in and that affected things. But the UMC is running off a sub panel and the electric heat off the main panel. The house has 200 amp service too so I wouldn't think this would be an issue.
     
  19. wk057

    wk057 Senior Tinkerer

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    It doesn't always warn, in my experience.

    90 ft of #6 running from a sub-panel with a ???A main and #? wire of ??ft to the main panel is probably enough to cause a pretty substantial voltage drop even with nothing else running let alone normal loads (especially resistive electric aux heat). You're looking at 4-5V drop just in the 90 ft of #6 @ 40A, plus a drop in whatever the run from the subpanel is to the main panel. Plus a drop when adding in the subpanel loads and main panel loads.

    Keep in mind that the NEC suggests a max voltage drop in a run of about 4V. You're definitely seeing more than that at 229V/30A. Service size doesn't help if the run is too long from the main panel.

    Sounds like you should have a run direct from the main panel, at the very least, IMO. Generally if it's going to be over 100' or close to it you should bump the conductor size by one (in this case, use #4) to limit voltage drop. Then you can use a junction box near the outlet to drop back to #6 if needed to connect to the outlet.

    Otherwise it is likely you'll continue to have voltage sag issues, and the car will do the safe thing and lower the current.
     
  20. hingisfan

    hingisfan hingisfan_Mark_V

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    Thanks for explaining that so well....I never knew much about voltage drop...sub panel is 100amp and is a 60 foot run from main panel. If I would have run direct from the main panel it would have been a 150-170 foot run, so I'm not sure if I would have been any better off, and running #4 that distance would have cost a fortune. I can live with charging at 30amps, I am just trying to determine if its likely an error my installer made, a defect in the car or UMC, or just my general setup/household load that is to blame. I'm glad the UMC is that smart to throttle down for potential issues.
     

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