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Service Voltage Drop and car reducing amps

Discussion in 'Model S: Battery & Charging' started by GJ79, Jul 18, 2016.

  1. GJ79

    GJ79 Member

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    So I am kind of lost on what is causing the car reducing the charging amps. I usually arrive home around 5ish in the afternoon to a piping hot Florida Garage. The car starts charging at 40 amps and 248 Volts and once it's ramped up the Service voltage is around 242Volts. The car keeps charging at 40 amps for at least 90 mins and then ramps down to 32 amps. I wonder if my grid tied solar system might also have an effect on this and causes fluctuations in the voltage as it happens around sunset or if the UMC detects the high temperature in the NEMA 14-50 plug. It seems that when I plug in later around 10PM the car never has to reduce the amps.
     
  2. mblakele

    mblakele radial cross member

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    You say the garage is hot? Maybe the battery pack gets too hot and that's why charging scales back? Can you hear the battery cooling system running the fans? Is the garage cooler around 10 PM?
     
  3. GJ79

    GJ79 Member

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    No the Battery cooling system is not running. Yes I'd say the garage gets cooler a couple degrees at night but also the Solar System is not producing any energy that late anymore.
     
  4. MSullivan

    MSullivan Member

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    I have solar and the exact same issue. But my charger is in the same sub-panel as my geothermal. When the geo kicks in the lights dim so it could be that as well.
    One of us could disable the solar for a day and see if it still happens. Picking a gloomy day would offset the lost production. You go first. :)
     
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  5. GJ79

    GJ79 Member

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    I live in Florida - we have no gloomy days :)
     
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  6. MSullivan

    MSullivan Member

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    Doh!
     
  7. GJ79

    GJ79 Member

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    So I actually turned of the solar last evening before plugging in the car and indeed the car kept charging at 40amps without reducing it's current. I will do a second trial next week to confirm but it seems the voltage fluctuations that are caused by the inverter effect the charging rate of the tesla. Any recommendations on how to prevent this?
     
  8. MSullivan

    MSullivan Member

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    Charge at night, I like to charge during the day because it feels good to know it is really solar but it is truly a push in the grand scheme. You are feeding more into the grid during the day that way. If your daily drive allows it set it to charge at 28 amps and just let go. You will never see that message again.
    I am actually testing mine right now because the temp is so cool today (it is 66 in the house this morning) that the geothermal won't kick on.
    My solar is producing 8.4 kWh and so far so good.
     
  9. GJ79

    GJ79 Member

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    Doesn't work like that for me as I often have to recharge just for an hour or two to make an additional evening trip. I wonder if upgrading to an 80amp HPWC would help or if it would also dial back to 32 amps.
     
  10. MSullivan

    MSullivan Member

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    Bet it would dial it back.
    I just dropped down to 30 amps so I guess it is the solar as well.
     
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  11. MSullivan

    MSullivan Member

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    You need an 240 volt 80 amp battery backup that would smooth out the fluctuations. Don't know if they make one but I bet it would cost a fortune.
     
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  12. Electric700

    Electric700 Member

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    Or may be a setting on the solar inverter (DC to AC) can be adjusted?
     
  13. mikeash

    mikeash Active Member

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    I seem to recall that the car always backs off by 75%, and the only step beyond that is shutting down the charge entirely. If I got that correct, then charging at 80A would cause you to drop back to 60A, and then either hold there (good!) or, if the extra amperage causes more trouble, stop (bad!). That's if you have dual chargers; if you just have the one, then having an 80A HPWC wouldn't make a bit of difference. If you have a refresh with the 48/72 charger, then it would be similar, but with 75% of those numbers instead.

    I'm no expert, but I imagine there are ways to filter the power from the solar equipment that might help this.
     
  14. MSullivan

    MSullivan Member

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    I have 62 panels each with their own micro inverter, that sounds like a lot of work.
    I'm just staying at 30 amps, I really cannot imagine when that won't be OK.
     
  15. GJ79

    GJ79 Member

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    Well, it shouldn't happen so therefore it's not OK, It's caused by something that shouldn't do this. If there are fluctuations that the care senses I would think these fluctuations can also effect other electronics in your home. I got in touch with my solar installer to see if there might be a setting in the Solaredge inverter than can be changed. The owner is also a fellow Tesla driver so I would think he would be very curious to figure this one out :)
     
  16. MSullivan

    MSullivan Member

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    I haven't isolated it to my solar panels yet. Next gloomy day I will turn them off and try charging.
     

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