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Instead of Robot Chargers, WIRELESS!

Discussion in 'Model S' started by tanner, Jan 12, 2016.

  1. tanner

    tanner Active Member

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    #1 tanner, Jan 12, 2016
    Last edited: Jan 12, 2016
    I hope the whole robotic charging arm concept is intended for just superchargers and not a pricy "sold separate" option to make the 'summon' feature truly great. Instead of selling a possible robot charger, why don't they just develop something similar to the drive-over wireless charger for the leaf? Sure, it would charge slightly slower, but it would be well worth it IMO (especially with summon): Meet the Plugless Level 2 wireless EV charging station
     
  2. LargeHamCollider

    LargeHamCollider Battery cells != scalable

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    Slower charging, less efficient, heavy on-board equipment needed, marginal cost differential if manufactured at scale. I used to think wireless charging would be cool but robot charging is a superior solution.
     
  3. Nismode

    Nismode Member

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    This is cool. They said they have something in development for the Model S. Would be great to have at home in a garage or driveway.
     
  4. Jool

    Jool Member

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    The big problem I see is that wireless charging is horribly inefficient. Not sure it would be worth the expense.
     
  5. tanner

    tanner Active Member

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    Apparently that company is already working on a solution for the MS. I think if Tesla implemented it at a factory level, it could be done right. Also, I don't agree that it's a "superior solution", seems more costly to purchase the robot than it would to have wireless included at factory/a package that came with the base.
     
  6. Bangor Bob

    Bangor Bob Member

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    Maybe it's already in the underbody shield and just needs a software update to enable!

    (I'm joking, really! But it would have been a great idea at the time.)
     
  7. tanner

    tanner Active Member

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    Just like I wish tesla would have included AP sensors in my car since they had planned to include it since before it even went into production. Haha. Tesla is in it for the money, of course.
     
  8. LargeHamCollider

    LargeHamCollider Battery cells != scalable

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    You could be right, but I suspect the costs will be comparable.

    My other points stand regardless, there is no practical user-facing functional difference between the technologies save where they'll be located in the garage (which could be an issue for some). Correctly implemented both provide "I don't even have to think about it" convenience; but one is faster, more efficient and doesn’t increase the mass of the vehicle.
     
  9. brkaus

    brkaus Member

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    I read a study that put the most efficient wireless phone chargers at somewhere around 65%. That is at much closer distances. I found a study that claims a wireless leaf charger can be 91% efficient. That's a good bit of loss if everyone was using wireless charging.
     
  10. tanner

    tanner Active Member

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    i still think the robot would cost more and I think that if Tesla were to implement wireless, they could do so without drastically increasing the weight. Moreover, the robot will have a higher failure rate. Moving parts = an increased likelihood of failure. I doubt they'd want to replace them for customers under warranty.

    - - - Updated - - -

    91% efficient is only a 9% loss, that seems pretty great to me.
     
  11. SomeJoe7777

    SomeJoe7777 Marginally-Known Member

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    That system is only 3.3 kW, which is only about 10 miles per hour of charge. It would be over 24 hours to fully charge a Model S.

    You simply can't get a high amount of power transfer inductively when there's an air gap. (e.g. The entire system acts like a transformer, with the primary winding in the garage floor and the secondary winding in the car). But when there's an air gap between the cores, the magnetic flux just can't get very dense. The only way around that is to increase the cross-sectional area of the core, which adds weight (core material and windings) to the car, which is the last thing you want. Also at that point, the material cost is rising to the point where the robotic arm can probably be made with cost parity.
     
  12. tanner

    tanner Active Member

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    #12 tanner, Jan 12, 2016
    Last edited: Jan 12, 2016
    Well yeah, but the leaf has significantly less range than a MS. I'm not saying adapt their exact tech, I'm saying tesla should look into a comparable solution. Also, air gap could be decreased on cars with air suspension, they'd just need to go into the low setting that tesla removed (wouldn't completely eliminate it, but it would help)
     
  13. SomeJoe7777

    SomeJoe7777 Marginally-Known Member

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    If you could somehow make the cores contact by either lowering the car or raising the primary winding from the floor, then the system can be made a lot more efficient, but at that point:

    1. You're introducing robotics and moving parts into the floor unit, which is what you were trying to avoid. Or you force all cars to have air suspension, and many don't.
    2. You now have an alignment issue, because the core will heat up with hysteresis and eddy current losses if the two parts aren't aligned.
    3. If you're making something in the floor contact something on the underside of the car, then at that point you could just do electrical contacts and eliminate the transformer entirely.

    No matter what, the secondary of the transformer in the car adds weight and impacts efficiency.

    Further, the transformer can only transfer AC, thus your power limit for charging is the limit of the on-board chargers -- 20 kW max or 10 kW in the majority of cars which can only reduce the full-charge time to 4.5 or 9 hours. For anything faster, you still have to have the charge port so you can charge with DC.

    Seems more trouble that its worth, given that a robotic arm is straightforward, compatible with all cars, and has no efficiency losses compared to standard charge cables.
     
  14. LargeHamCollider

    LargeHamCollider Battery cells != scalable

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    I'm afraid I'm coming off as a big killjoy in this thread but I'd be absolutely shocked if Tesla hadn't looked into it. 9% may not seem like a lot of loss (and I suspect that the necessarily higher power Tesla version would have lower efficiency) but Tesla is planning on having millions of cars on the road, this 9% will turn into GWhs pretty quickly.
     
  15. tanner

    tanner Active Member

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    Assume the floor unit doesn't move & just sticks up slightly by nature, then the lowest setting for air suspension (it can go lower than Tesla allows you to set it) will work fine. As for your "compatible with all cars", we all know Tesla favors planned obsolescence and will continue innovating without retrofit options to sell more cars.

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    Irrelevant if we make the switch to renewable energy. Moreover, it doesn't have to go to waste. Could be re-captured or passed along to a home battery (e.g. power wall).
     
  16. politeperson

    politeperson Member

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    What you really want is the ability to wirelessly charge whist driving.

    Even is only a percentage of the charge being consumed was replenished, it would extend your range significantly over say 100 miles.

    Now, if they could just bury something in the road, that would be picked up in the car, producing a current over the battery terminals, that would be excellent.
     
  17. DFibRL8R

    DFibRL8R Member

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    Apparently there is something along these lines under development in the U.K.
    UK to test new roads that charge cars as they drive - Aug. 18, 2015
     
  18. asudan

    asudan Member

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    With SUMMON - why not make some kind of connection point in the front of the car and have it drive into the charger automatically. Hell if a ROOMBA can do this, why couldn't an MS? Wireless charging is sexy but as others have said it is really inefficient and would add a lot of cost to the user. (you think installing your mobile charger was expensive - ask about running power to the floor of your garage!)
     
  19. brkaus

    brkaus Member

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    I'm thinking all they need is:

    1. Auto park/summon

    2. The appropriate wall adaptor

    3. The new front mount charge accessory.

    e9038718962f3ae150f21ef798f43d10.jpg
     
  20. brucet999

    brucet999 Active Member

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    "91% efficient is only a 9% loss, that seems pretty great to me."

    9% loss = 11% more power consumed to get to the same SOC in the car. Add approximately 2% line loss in house wiring between meter and charging outlet and you are paying 13% more to charge and consuming 13% more power generation resources (coal, natural gas, etc.) thus making your car less green and consuming more non-renewable resources; all to avoid sticking a plug into your car by hand.
     

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