ALTA death spiral and crash

Discussion in 'ALTA' started by Adam Varadi, Nov 26, 2015.

  1. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    That's so strange isn't it, Dejan -- given those dire warnings in the manual.
    Every XT90 that I have ever seen is likely to connect up both the positive and the negative terminals either at the same time, or in some random way -- I've never seen XT90 that connect the negative before the positive.

    I am trying to download the manual but Graupner has a screwy web site where I cannot enter my full username....just curious to see if there is a new manual without the restrictions of negative->positive->balance leads.

    Andy.
     
  2. Gary Haynes

    Gary Haynes Administrator
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    Lanzar the hookup and electrical operation of the Synapse may be different than the flight electronics you are using. As stated in the report there was no one conclusion just good observations of a couple of different scenarios. This is a No Jinx Zone :)
     
  3. Taylor Davis

    Taylor Davis New Member

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    I had one of these Graupner air modules a little while back and it fried one of our DJI A2 "controller units" during the first bench test. Somehow got DJI to cover the A2 and replaced the bad unit. Took the time between the shipping to test the Granpner air module to figure out it was the reason. Emailed Graupner, no answer, called the US reseller, they told me to go get bent. Long story short, don't use Graupner anymore. Sorry about the crash, very cool of FF to send you a replacement. Thanks for letting all of us know about your experience.

    Taylor
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Taylor: Did you ever figure what might have caused the Graupner EAM to fry the A2?

    Andy.
     
  5. Adam Varadi

    Adam Varadi Member

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    Hy guys,

    I was busy in the last few months but finally got time to test the XT90S connectors.
    I tested the boot up with the XT90S connectors and with the Herkules antispark. Herkules says it only limits the current, but in the tests I found out it acts like a current generator. ( http://www.kopterworx.com/herkules-iii-precharge-board.html )

    IMG_1666.jpg

    So I made 3 different pictures of the osciloscope, each with different time setups. These test were done on my Hammer X8. (one square is equivalent with 5V)

    Here are the XT90S:

    IMG_1667.jpg IMG_1669.jpg IMG_1670.jpg

    As you can see these connectors are terrible. :)
    The big gap is when the connector with the resistor doesn't connect anymore but the normal connector is still not connected.
    The voltage drops quite a lot, no matter how quickly i tried to connect them.

    And here is the Herkules Antispark:

    IMG_1672.jpg IMG_1673.jpg IMG_1674.jpg

    You can see it's much more clear, have a nice linear power up, and one important thing is tha max voltage through the antispark and the max voltage of the big connectors are almost identical.

    I would strongly recommend not to use XT90S! Or if you are like me use them but with the Herkules antispark, this way the copter is safe, and when charging the batteries there are no sparks.

    There is no proof that the XT90S can cause trouble, but its wise to eliminate every small possibility.

    Tabb or anyone at Freefly, if you like share this info, it could save copters and even prevent injuries!!!
     
  6. Rolf Ableiter

    Rolf Ableiter Active Member

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    thanks for this, Adam!
    thats what the guys at globeflight figured out too and this is why i told this here at the forum.
    It is good to hear, that Andreas Baier (herkules) made a good job with his antispark system. I still use a cinestar with herkules 3 and dji as backup but without antispark and i think i will update the herkules now.
     
  7. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Thanks for the systematic research Adam. Nice to see real world data rather than just anecdotal evidence!

    Andy.
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Thanks for the systematic research Adam. Nice to see real world data rather than just anecdotal evidence!

    Andy.
     

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