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77 kW ?? TED reading spike - make sense?

Discussion in 'Model S: Battery & Charging' started by Electricfan, Jan 7, 2016.

  1. Electricfan

    Electricfan Member

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    #1 Electricfan, Jan 7, 2016
    Last edited by a moderator: Mar 13, 2016
    I recorded my TED meter last night just to watch the power levels. I've got a new meter on order that I can monitor on my phone, so I'll have a better system soon.

    The TED is reading the total house power draw. The CTs are right at the point where the feeder wires land in my main circuit breaker panel.

    Anyway, if you watch the video you see the power spikes to 77kW for almost 10 sec. I'm wondering if that is indicating a problem in my house wiring, in the charger on the Tesla, or its just a false reading from the TED? Opinions?

    The house draws less than a kw when the heat and AC are off (and no car is charging and water heater off). The 5kw reading at the beginning of the video is due mostly to the Tesla charging. I have a L2 charger and I set the current draw on the Tesla to 20 amps. The spike occurs when the house heat kicks on. I know motors have inrush current, but should a home heating system have that kind of inrush? I'm really puzzled if the 77kw is real or not.

     
  2. FlasherZ

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

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    77 kW could be reasonable, but not for 10 seconds. That *should* trip a breaker somewhere if it goes on that long. Does TED use PLC for communication? If so, it's possible that the EMI prevents the TED from receiving the senders' updated readings until the motors calm down.

    You don't mention what type of heating system you have - heat pump, aux heat, etc. It is certainly possible to hit 77 kW, but it would only be only for a second or so. At the instant a motor is energized, it's going to draw about 12x its fully loaded current to charge the capacitor and start the motor, that will decline to about 6x its loaded current as it begins spinning, and then will pull back from there. But that whole process should take about a second maximum. Bad start capacitors and bad bearings may extend that time and cause more-than-usual light dimming. If it's a simultaneous-start heat pump system where the blower, compressor, and even perhaps aux resistive heat kick in at once, you could easily measure 77 kW for a short period of time.

    My guess is that the TED managed to measure usage at the precise moment that the system started.

    Do you see extensive light dimming, and for how long, when the heat kicks in? That will be your indication as to how long you're drawing that 77 kW.
     
  3. Electricfan

    Electricfan Member

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    Yes, it uses PLC. I notice it is very slow to update - I can hear the heat come on (no dimming of the lights, unless it is a quick flicker that I've gotten used to) and it will run for a few minutes before the TED shows any increase in power usage. Same when the AC kicks on.

    I'm sorry I can't tell you much about the heating system - it isn't a heat pump, and it isn't natural gas. All I can say is it is a big box in a sort of closet in my garage.

    When I get the new power monitor (Neurio - found on Amazon) I'll see what it shows. Hoping it is quicker to show live usage levels.
     
  4. FlasherZ

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

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    I think you're just fine and you caught a momentary snapshot of a motor start. I wouldn't worry.
     

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