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50A blue commando

Discussion in 'Roadster' started by Perrin21, Jul 30, 2014.

  1. Perrin21

    Perrin21 Member

    Joined:
    May 18, 2014
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    Location:
    uk
    Hi, if I provided my blue commando with a 50A breaker, would my UMC work at 50A for charging my roadster?
     
  2. sethr

    sethr CPO Roadster #1089

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    Mar 24, 2013
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    Fairfax, VA
    No. You can only charge at 80% of the breaker's amperage. Therefore, with a 50 amp breaker, you can charge at 40 amps.
     
  3. Perrin21

    Perrin21 Member

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    Location:
    uk
    Ok so if i fit a 63A breaker would the 30A UMC still be upto the job for 50A?
     
  4. sethr

    sethr CPO Roadster #1089

    Joined:
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    Location:
    Fairfax, VA
    According to my UMC user's manual, the limit is a 40 amp draw for North America, and 32 amps for "Rest of World", which I guess includes the UK. Maybe someone on this forum who has knowledge beyond what the manual says can give some further input, but it sounds to me like that's it. Personally, I only charge at 24 amps, because I am on my third UMC, and I was told that lower amperage = lower charging temperature, and Tesla Service said part of the reason for their failure was that they were getting too hot during charging.
     
  5. slcasner

    slcasner Member

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    No, because the 30A UMC contains a circuit to generate a pilot signal indicating that the maximum current it can deliver is 30A. That tells the car to not draw more than 30A. You would need a new circuit to produce a pilot signal indicating 50A capacity. (Depending upon how the circuit works, it might be possible to accomplish this change by changing firmware in the circuit.)

    I don't know how the 30A UMC that you have compares to the original 30A charge cables provided by Tesla in the US, but the latter devices contained a GFCI that was rated for only 30A. That is why the unit was limited to 30A and not 32A (that a 40A breaker allows) or 40A (that a 50A breaker allows and that matches the NEMA 14-50 connector that the cable came with). I was told that Tesla could not find a suitable GFCI for the higher current.
     
  6. Kevin Sharpe

    Kevin Sharpe Active Member

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    Bradford on Avon, UK
    The Tesla UMC is limited to 32A in the UK. You could build your own portable EVSE (I have a 63A EVSE) but you'll find very few "command" sockets with more than 32A in the UK.

    In the UK we don't do the 80% current derating that they do in the US so just ignore all those comments :smile:
     

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