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Charging from a generator.

Discussion in 'Roadster: Technical' started by Tesla 940, Dec 27, 2013.

  1. Tesla 940

    Tesla 940 Member

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    I have a 7kw gas powered generator (8,750 max) that I would like to be able to use to charge my Roadster. I built a cord using the proper male 30 amp plug to insert into the generator's 240 outlet and have a female 14-50 on the other end. I insert my UMC 14-50 into this new cord and then attach the cord to the car. I'm registering ~245 volts. When I attempt to charge (initially at only 15 amps) the car cycles through the start-up process - blue flashing - then goes to white and immediately to red. The car's display says "Line Voltage Lost Sync" and then a second screen is displayed "External Charger Problem".

    Can any of you help?

    btw - I had no problem using the 110 charger cord at 12 and 15 amps.
     
  2. AmpedUP

    AmpedUP EV Nut

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    'Sounds like the sine wave of the generator output is not stable. Generators and UPS devices with poor waveform can do damage to electronics. 'Good thing your Roadster knows enough to check before accepting. Newer generators have cleaner outputs, depending upon the model.
     
  3. Raffy.Roma

    Raffy.Roma Active Member

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    I read that the Roadster accepts only pure sine generators. Maybe that your generator is not pure sine?
     
  4. Doug_G

    Doug_G Lead Moderator

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    Roadsters are very fussy. Transport Canada tried six different generators of different vintages and none of them worked. You need to have a very clean sinewave output, very low harmonics, and stable frequency and voltage.

    Also I believe there's already a thread on the topic... if I can find it I will merge.
     
  5. Tesla 940

    Tesla 940 Member

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    Thanks for the quick responses.

    Since I know nothing about sinewave output - is it logical that the 120 volt 12 or 15 amp works and the 240 volt 15 amp does not?
     
  6. Raffy.Roma

    Raffy.Roma Active Member

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    @Tesla 940

    It could be that the 120 V outlet sine wave of your generator is cleaner than the 240 V. That's why it works only with the 120 V outlet.
     
  7. captain_zap

    captain_zap Electron tamer

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    All high power chargers that are any good these days are power factor corrected, to extract the most possible power from the source. This means they try to look like a pure resistive load (not capacitive nor inductive). They try to draw a current waveform which ratiometrically tracks the AC line voltage to the peak, where it draws the most current. If the voltage waveform is distorted with high frequency harmonics (which many generators are), the power factor control circuitry can't track the input waveform and can cause current limiting and faults in the main high frequency switching stage.

    There are inverter-generators on the market which have high power DC generators feeding solid state inverters, producing clean sine waves. I'm pretty sure these would work with the Roadster. Haven't seen one above 5 kW, though.
     
  8. Marius

    Marius Member

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    Did you check the grounding of the generator? I know that a lot of generators have for safety reasons no grounding on the windings. The roadster needs a power supply with grounded windings on the neutral connector at the generator.
     
  9. spaceballs

    spaceballs Member

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    #9 spaceballs, Aug 24, 2014
    Last edited: Aug 24, 2014
    *** USE AT YOUR OWN RISK ***
    *Note only use Generators that have Inverter technology for clean power output suitable for computers and sensitive electronic equipment. Most large generators do not have this feature.

    I'm able to do a slow charge at 12Amps with my Honda EU2000i generator.
    The EU2000i doesn't connect GND with Neutral, so a quick stop at home depot fixed that, see adapter pics.
    Capture1.PNG
    Capture2.PNG
    Capture3.PNG Capture4.PNG
    Capture5.PNG
     
  10. Raffy.Roma

    Raffy.Roma Active Member

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    @spaceballs

    What is the rate (kilometers per hour) of this charge?

    Does the generator fit in the trunk of your Roadster?
     
  11. spaceballs

    spaceballs Member

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    120v * 12amp = 1440Wh (ignoring losses)

    User Thefortunes says they get on average 256 Wh/mi for their Roadster.

    So guessing ~5 miles (8 kilometers) per hour at this rate.

    I don't think so, but I'll check tomorrow
     
  12. Raffy.Roma

    Raffy.Roma Active Member

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    But this charge is too slow. IMO a generator able to do a charge at least twice faster is needed. Don't you think so?
     
  13. spaceballs

    spaceballs Member

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    This is a small generator, this generator can only sustain 1800 watts continually, I set the Roadster to charge at it's minimum (it was just a test). Honda does has larger inverter generators that would work with the Roadsters to charge at much faster rates.
     
  14. swaltner

    swaltner Member

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    Honda sells up to 7000 watt inverter based generators. However, at 250+ pounds and basically a 2.5' cube, the larger varieties definitely wouldn't fit in the trunk. Google "honda generator" looking at models with an i in the part number to see inverter based options. I really like my 2000i generator. Don't use it very often, but it's so convenient and quiet.
     
  15. Raffy.Roma

    Raffy.Roma Active Member

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    Good that it fits in the trunk of your Roadster and that it's quite but 8 kilometers per hour are not enough IMO.
     
  16. spaceballs

    spaceballs Member

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    The EU2000i doesn't fit in the trunk of the Roadster, I can put it in, but I can't close the lid as it's about 3-4 inches to tall. Though I sure it would fit in the frunk of the model S.

    Well if I did every want to carry a generator, there is already a trailer hitch on the Roadster so I could connect an cargo tray to it, and put two EU2000i on that.

    Any of the Honda EU inverter models you can put them in parallel for more KW's, I can put two of them and get ~3.6kwh, i.e. I use that as my house backup generator.
     
  17. Raffy.Roma

    Raffy.Roma Active Member

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    Agree but then I would prefer to wait for the upgrade of the battery pack in 2015. To me it looks more practical. :wink:
     

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