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HV Contactor Longevity

Discussion in 'Model S: Battery & Charging' started by gavine, Feb 16, 2015.

  1. gavine

    gavine Petrol Head turned EV Enthusiast

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    How durable is the contactor supposed to be? The reason I ask is because I understand that it is a relatively expensive part to replace and it bothers me that the contactor opens every time a door gets opened. Whenever we go out as a family (almost daily), we all seem to get In the car within a few minutes of each other so he contactor opens and closes multiple times. Then another time when it charges. Then when we get home, someone will go back to the car to get something out that was left in the car...another contactor open/close cycle.

    Is is this something about which I should be concerned?

    Why does the contactor need to close whenever a door is opened? My thought is because the car has a "feature" that turns on the HVAC when you open the door, which brings up another concern....I hate the the AC turns on if I just need to open the door for a second. I know I can turn off the HVAC when exiting the car so that doesn't happen, but my wife doesn't do that.

    If if that's the only reason the contactor engages when opening the door, it would be nice if that didn't happen if the HVAC was off. This would save the contactor from unnecessary cycles.

    Thoughts?
     
  2. kennybobby

    kennybobby Member

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    #2 kennybobby, Feb 16, 2015
    Last edited: Feb 16, 2015
    The datasheet for a similar contactor by the same vendor indicates it has a mechanical life rating of 1 million cycles and an electrical life of 1 cycle to break under load at 320V and 2000A.

    Make/Break Life Capacitive & Resistive Loads at 320VDC (1) (2)

    @90% capacitive pre-charge (make only) 50,000 cycles

    @80% capacitive pre-charge (make only) 50 cycles

    @200A make/break (2 consecutive, reverse polarity) (1) 12 cycles

    2,000A (break only) (1) 1 cycle*

    Mechanical Life 1 million cycles

    (1) Resistive load includes inductance L = 25μH. Load @ 2500A tested @ 200μH.
    (2) Life based on projected Weibull Life with 95% teliability.
    * Does not meet dielectric and IR after test.
     
  3. gavine

    gavine Petrol Head turned EV Enthusiast

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    Thanks much...I feel better now. 1 million cycles explains why Tesla isn't too concerned about cycling it so often.
     
  4. mknox

    mknox Well-Known Member

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    Not sure, but mine is on the recall list to have the main contactors replaced. My SC said they'd call me when it's my turn. I think they have to swap out my main battery pack with a loaner while they do the repairs.
     
  5. dsm363

    dsm363 Roadster + Sig Model S

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    That's what they are doing with my pack.
     
  6. FlasherZ

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

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    I just went through this as well. In some cases, the service center can do this in less than a day. In other cases, you get a loaner pack while yours is being sent back. There is a field test they do to determine whether they replace your contactors at the SC, or whether it has to go back.
     
  7. pgiralt

    pgiralt Active Member

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    They did mine at the service center in a day. Depends on whether or not someone at the SC has been trained on the procedure.
     
  8. rlang59

    rlang59 Member

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    Same here, done at service center in less than a day. In my case I got a call from the Queens service center which is trained to do the work but is not my usual one.
     
  9. andrewket

    andrewket 2014 S P85DL, 2016 X P90DL (soon 100)

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    I would prefer a delay engaging the contactor too. My kids frequently won't open the rear doors until after I've closed the front doors, causing an extra cycle. And then when you go back to get groceries, etc, it does it again. In the summer I've taught myself not to close the door until we're completely done.
     
  10. snellenr

    snellenr Member

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    Assuming for the sake of argument that kennybobby's contractor has a similar rating as Tesla's part, a rated lifetime of 1,000,000 cycles results in a 25 year lifetime even if they cycle 100 times a day.
     
  11. wycolo

    wycolo Active Member

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    The 1 million cycles rating is with no current flow. Similar to testing a door latch.

    Now look with current being switched:

    > @80% capacitive pre-charge (make only) 50 cycles
    > @200A make/break (2 consecutive, reverse polarity) (1) 12 cycles

    Some of the thrill is gone, right? Maybe think twice before that next big launch, out in the boonies.

    To the OP: how, where do you listen for contactor closing sound? I've tried but not sure I'm hearing it. And I have some power train noise that I'm always monitoring. I always assumed the contactor would clunk ON when the car goes ON, and the power unit would thereafter be controlled by the solid state relays in the inverter section as you transition between: regen<->coast<->accel. Until car goes OFF or, god forbid, you hear the 'clunk of death'. :eek:
    --
     
  12. gavine

    gavine Petrol Head turned EV Enthusiast

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    I'm glad I'm not the only one......but, with this 1-million cycle rating, I have to say I'm very much less concerned now. I still think it should not engage the contactor until you actually turn the car on or turn-on the HVAC. It shouldn't engage just by opening a door, especially the back door.

    - - - Updated - - -

    When you open a door, you hear the door latch and the contactor almost at the same time. When the contactor engages, it's a fairly loud "snap" sound. After you close the doors, about 2 or 3 seconds later, you hear a muted clunk which is it disengaging. You can also hear it when you plug-in to charge after the doors have already been shut and contactor has been disengaged.
     
  13. wycolo

    wycolo Active Member

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    Plug-In to charge = clunk

    Ok, I always hear this one, as I'm looking for the LED ring to light up, but I assume this is coming from the Charge Relay Box (the one in the middle, between the twin chargers). This clunk is loud since this box is open to the interior and I have no back seats to muffle the sound. If this clunk is actually coming from inside the battery box it would be further underneath and therefore more muffled. I'll investigate.

    Also, my evse clunks (loud) at the same exact time (?) and it is only 6 feet away.

    [2012 with B battery]
    --
     
  14. gavine

    gavine Petrol Head turned EV Enthusiast

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    The first clunk when you plug in the charger is the lock actuating. That's not the contactor. Once the charging process starts, that's when the contactor is heard. Keep in mind that you won't hear it if the doors are still open. If you want to test it. Close the doors and listen for the muffled clunk. Then plug-in and make sure it is set to charge. You'll hear the contactor then.
     
  15. kennybobby

    kennybobby Member

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    There is a pair of HV contactors (for pack On/Off) in the battery pack, and there is another pair only used for DC supercharging in the High Voltage Junction Box (HVJB) located under the rear seat between the chargers. The HVJB routes either AC to the chargers or DC to the pack, plus routes the feed from the pack thru a fuse to the DCDC converter or Front Junction Box depending upon vintage.

    There is a picture and schematic here: Battery Power-Up After an Accident
     
  16. FlasherZ

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

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    When I plug in my car, there's the "chunk" of the charge lock engaging to lock the handle in place. 1-2 seconds later there's a "click-click" from the battery pack contactors, then the "tick" from the contactor in the HPWC about half a second later.
     
  17. Newscutter

    Newscutter Member

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    I've certainly done more than 50 launches at 100% throttle. Maybe I'm misunderstanding the rating-speak? What does this mean real-world? Those numbers seem very low for a part warranted for 8 years.
     
  18. LuckyLuke

    LuckyLuke Model S P85DL

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    I would expect that current starts/stops to flow a few milliseconds after/before the contactor closes/opens, essentially creating a no-power window where it is safe to make/break contact. Would be silly to do this while fully powered, right? Therefor the cycles under load are not so relevant.
    Does that make any sense? :)
     
  19. mknox

    mknox Well-Known Member

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    Exactly! And the UMC makes a similar "tick" sound when it turns on.
     
  20. FlasherZ

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

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    Correct. If it breaks under load, you'll know it - the early packs that had the dreaded "clunk" created this condition. Under acceleration, it feels as if you are rear-ended.

    I really doubt there is a condition that would cause the car to make the connection under full load, unless there were some type of a major system failure.
     

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