TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker or making a Paypal contribution here: paypal.me/SupportTMC

Tesla Pilot Signal Details

Discussion in 'Technical' started by suxxer, Feb 22, 2011.

  1. suxxer

    suxxer ElektroVolt

    Joined:
    Dec 15, 2010
    Messages:
    294
    Location:
    Zurich, Switzerland
    Does anyone has details on the pilot signal (the extra pin inside the charge connector) Tesla is using? The pilot signal tells the car how much amps it can draw from a power source.

    According to the specs the "Spare Connector" allows 15 [email protected] in the US. My local Tesla dealer told me that they have [email protected] and [email protected] here in Europe. He told me they have "some modifications" on the cable in order to get 10 or 15 amps.

    The "Universal Mobile Connector" on the other side seems to adjust the max. amps according to the plug connected. If you connect a NEMA 6-30 plug it's 30amps, connecting a NEMA 6-15 plug it's 15 amps.

    Search yields some infos about the Pilot Signal Tesla uses. It seems to be a 12V 1kHZ square wave signal. It looks like the max current can be set by adjusting the duty cycle. According to the Avcon source a 50% duty cycle equals 30amps. (the ratio of the high period to the total period of a square wave is called the duty cycle. A true square wave has a 50% duty cycle - equal high and low periods.)

    Can someone confirm that? Does this mean that even the "Spare Connector" has a built-in circuit who supplies the desired pilot signal? And/Or does the absence of a pilot signal default the max amps to 10amps?
     
  2. jaanton

    jaanton Roadster NA #1026

    Joined:
    Jun 25, 2010
    Messages:
    312
    Location:
    Oakland, CA
    You want to read scott451's posts... The "Spare Connector" just ties the pilot pin to ground with the switch. (At least that's the USA version.)
    The "Spare Connector" is really following the "Level 1" protocol while the square wave stuff is the "Level 2" protocol.

    Charging the Roadster
     
  3. scott451

    scott451 KWH-PWR#1349Sprt,S Sig#96

    Joined:
    Apr 2, 2009
    Messages:
    251
    Location:
    Palo Alto
    #3 scott451, Feb 22, 2011
    Last edited: Feb 22, 2011
    Tesla follows the J1772 spec. (Troy N and other folks at Tesla were/are actively involved in defining the spec)
    IEC 309 is very simlar: http://www.park-charge.ch/documents/BOXSPECE.pdf


    For USA Roadsters, grounding the pilot pin (which is not part of J1772) allows the car to charge at 16A (80% of a 20A circuit) or 12A (80% of a 15A circuit). The NEC considers the EV as a "continuous load" hence the 80% derating. I've heard the [email protected] and [email protected] work the same way. No pilot, just a grounded pilot pin.

    I believe the UMC is a clone of the RFMC. The neutral pin is not used so Martin E. put a short/forward diode/reverse diode to ground in each of the adapters to indicate the available current.
    yes. It is a +12V/-12V square wave with a 1K ohm source resistance (as described in J1772)

    Correct. however Tesla modified the duty cycle equation above 48A to accommodate 70A charging. (this modification is now part of J1772-2010)

    I don't know what a "spare connector" is, but if it is like the 110V charging cable, then there is no pilot generator, the slide switch just shorts the pilot to ground.
     
  4. suxxer

    suxxer ElektroVolt

    Joined:
    Dec 15, 2010
    Messages:
    294
    Location:
    Zurich, Switzerland
    #4 suxxer, Feb 23, 2011
    Last edited: Feb 23, 2011
    Thanks for the reply. According to the website Tesla calls the yellow charging cable "spare connector".

    One thing still is unclear for me:

    But how does the car know how much power it can take (10A or 16A)? You will have some problems if you have a 10A breaker and the car starts to suck 16amps. In my opinion just grounding the signal pin won't do the job. A grounded signal pin maybe just defaults the charge limit to [email protected] (US) / [email protected] (Europe). If Tesla tells me that they have two verisons (10A & 16A) of the yellow cable then the grounded signal pin wont do the job alone...


    I took a look at Martins charger. The unit seems to work with the square wave signal on the output side. And it looks like it detects what plug you connect to the unit (on the input side) and sets the right charge limit. So here the limit is also detected by connecting the right plug.

    _MG_2281.jpg
     
  5. tomsax

    tomsax Member

    Joined:
    Jun 19, 2008
    Messages:
    867
    Location:
    Sammamish, WA
    #5 tomsax, Jun 19, 2011
    Last edited: Feb 19, 2014
    The RFMC looks for a diode between ground and what would normally be neutral on the twist-lock connector. If there is no diode, it assumes a 16A limit. If there's a diode one way, it signals 24A limit, if there's a diode pointed the other way, it signals a 40A limit.

    I don't know how UMC does it, something similar I would guess.

    If someone has the 10A/230V spare connector, it would be helpful to check for either a diode or resister between pilot and ground and post the results.
     
  6. marco2228

    marco2228 Roadster Signature #34

    Joined:
    Nov 19, 2010
    Messages:
    185
    Location:
    Cologne/Bremen , Germany
    Does anyone know what duty cycles Tesla used for the higher currents above 40 A?
     
  7. mitch672

    mitch672 Active Member

    Joined:
    Jul 1, 2012
    Messages:
    1,868
    Location:
    Stoughton, MA
  8. tomsax

    tomsax Member

    Joined:
    Jun 19, 2008
    Messages:
    867
    Location:
    Sammamish, WA
    Original Roadster HPC Duty Cycle Values

    I tested an original Tesla Roadster HPC, one of the early ones before they started using the Clipper Creek units. It has a rotary dial to set the current limit, so I could test every setting. It agreed to within 0.1% of the J1772 spec for all values.

    EVSE-Pilot-Signals.png

    That's no surprise since Tesla (specifically, Martin Eberhard) proposed using Tesla's extension to the 2000 version of the J1772 pilot signal spec to accommodate charging up to 80A.
     
  9. TonyWilliams

    TonyWilliams Active Member

    Joined:
    Jun 11, 2012
    Messages:
    1,001
    Location:
    San Diego - Tesla powered Rav4 EV

    IEC uses
    1.5k pilot to ground 13a
    680 - 20a
    220 - 32a
    100 - 63a
     

Share This Page