New Motors, New PDB... Three groups of currents?

Discussion in 'Cinestar 8' started by Ben Freedman, Mar 26, 2013.

  1. Ben Freedman

    Ben Freedman Member

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    Howdy...

    So, the QC folks replaced ALL my motors, and I have a brand new PDB. Checked and double checked everything. Balanced and leveled , yadda yadda....

    Take a look at this GPX file. My motor currents fall into 3 distinct groups... Low, Medium, and High.

    Motors 1, 5, and 7 seem high.

    Motors 3, 4, and 8 seem about right

    Motors 2 and 6 are low.

    Temps do not seem to correlate, however. ie. average BL temp on Motor 1 is basically the same as on motor 3.

    Average BL temp on motor 4 is about the same as motor 6. Even though the current is quite different.

    Flight seems very stable. AH and PH work fine. Balance is close to center. Motor level seem just about dead on.

    I'm wondering if anyone sees this, and perhaps it could be reporting incorrectly, or maybe it's just the way MK electronics are?

    Thoughts?

    bb
     

    Attached Files:

  2. Shaun Stanton

    Shaun Stanton Active Member

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    What were the winds like? I have had oddball response when flying 25 Mph winds before. Although your numbers don't make sense. I ran a few regression models. And all even motors seem to be effected by you pitch angle.

    I regressed 5 against 8 and found that 5 really is inducing something on 8. Almost no response to 6.

    8 is inducing something on 2 to cause to ramp down.

    Not sure what could be causing it. The odd temperatures are to be questioned. It could be cold solder joints, where the connection on the BL is not as conductive as you would expect it to be. That would cause those temperatures to be high at lower current pulls.

    Do you have a picture of the board?
     
  3. Ben Freedman

    Ben Freedman Member

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    I'll post one when I'm back in town net week. However, bad solder joints would cause the correlation that you're seeing, no?

    This was a dead calm zero wind day.

    Very odd..

    B.
     
  4. Shaun Stanton

    Shaun Stanton Active Member

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    It's a reasonable possibility for the temperature abnormalities. As for the motor current's being off not sure what would induce it other than out of balance aerodynamic forces from the engine thrust.

    Shaun
     

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