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HELP! What the heck happened here?

Discussion in 'Cinestar 8' started by Ben Freedman, Feb 4, 2013.

  1. Ben Freedman

    Ben Freedman Member

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    Howdy...

    Still in my initial training days with my new C8 and this has me stumped...

    A nice easy flight today, not to heavy, just a handycam on board. Everything is fine, but as I come into land, Motor 4 shuts down! BL Overload? What on earth?

    I've uploaded the GPX File. I sure hope someone can help me figure out what happened. Managed to land it safely, as I was coming in to land anyways, but what was the problem?

    Thanks for any help you can offer...

    Ben
     

    Attached Files:

  2. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Looking at the file now...

    Josh
     
  3. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Looks like you had motor 4 go WAY overtemp...

    Flight time: 10:16:52 AM - 10:19:43 AM (171 secs, 00:02:51)
    Total: 371 secs, 00:06:11
    Elevation(GPS) : 0 5.11 13.277 m
    Altitude(Barom.): -2.35 3.41 12.05 m
    Vertical speed : -1.53 0 1.7 m/s
    Max speed : 9.6 km/h
    Max target dist.: 0 m

    Sats: 10 12 13 (min/avg/max)

    Voltage: min. 14.6, max. 15.7 V
    Current: 5.4 47 62.3 A
    Wattage: 82 712 940.73 W
    Capacity: 4922 mAh

    Motor1: 0.4 6.5 8.7 A Temp: 38 71 83 °C
    Motor2: 0.7 6.4 12.6 A Temp: 43 76 87 °C
    Motor3: 0.5 6.5 8.7 A Temp: 37 57 67 °C
    Motor4: 0.0 5.1 11.1 A Temp: 35 67 147 °C
    Motor5: 0.5 6.3 11.9 A Temp: 35 51 57 °C
    Motor6: 0.7 5.7 11.2 A Temp: 34 49 55 °C
    Motor7: 0.6 5.9 8.3 A Temp: 36 54 61 °C
    Motor8: 0.0 2.9 4.2 A Temp: 38 59 71 °C

    Magnet Field: 99 101 105 % (ok)
    Magnet Inclination: 55 58 64 deg

    Errors / warnings:
    Error "Motor restart" (23) occured 7 times!
    Error "BL Limitation" (24) occured 9 times!
    FC-Flag "LowBat" (5) occured 1 times!

    Im trying to figure out why though.. looks like all the other numbers were ok?

    Josh
     
  4. Ben Freedman

    Ben Freedman Member

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    Howdy...

    So, I just did a quick on-ground test. No flight, so no log file, but almost immediately, Motor 4 was starting and stopping by itself. It would stop, then restart after a few seconds, then stop again.

    Saw some smoke coming from the PWD too...

    So, does this mean that motor 4 is fried? BL 4 is fried? Both? How and why could this happen? What should I do to rectify this?

    Thanks!

    Ben
     
  5. Josh Lambeth

    Josh Lambeth Well-Known Member

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    I am guessing that is the case. 147*C is just under 300*F! They fail at 115*C. I am wondering what caused that. Are you using heat sinks?

    Josh
     
  6. Ben Freedman

    Ben Freedman Member

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    No... as you know, it's still nice and cool here in AZ. No heat sinks...

    So, what now? What do I replace? What was the cause? Is this a warranty issue?

    Best,

    Ben
     
  7. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Can you post a picture of BL4 how it sits currently with everything around it? Wondering about the cooling.

    Josh
     
  8. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Also do you have the video you were shooting when this happened?

    josh
     
  9. Ben Freedman

    Ben Freedman Member

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    Howdy...

    I do have the video. It's uneventful, although you can see some smoke when the motor fails...

    Here's a photo of BL4.

    [​IMG]
     
  10. Josh Lambeth

    Josh Lambeth Well-Known Member

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    You can see in this graph how all the other motors started cooling down at the point that motor 4's temps skyrocketed. Hmm.... Ben_Overtemp.jpg
     
  11. Josh Lambeth

    Josh Lambeth Well-Known Member

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    I would pull the PD board off and check the Caps on the bottom of the board. Take a pic. Also please post the video. Thanks!

    josh
     
  12. Ben Freedman

    Ben Freedman Member

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    The other motors begin cooling because I was landing at that point. I was only 4-5ft from the ground when this happened...

    I'll work on the other items, and on getting you some video to watch...

    Best,

    Ben
     
  13. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Just out of curiosity, How did the copter handle loosing a motor?
     
  14. Ben Freedman

    Ben Freedman Member

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    Here's the last minute of the video...

    The copter seems to handle the loss of the motor well. With a light load, I'm sure I could have maintained altitude for a short while...

    Removing the board now....

    Ben

     
  15. Ben Freedman

    Ben Freedman Member

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    Update...

    I tried switching over BL3 and BL4, and it appears motor 4 is fine. Motor 3 (when attached to BL4) was still giving problems... So, it's definitely BL4. I have another BL from an previous board, so I will try to unsolder one of those and use it on here...

    By question is... why and how did this happen? I have NO clue... Argh!

    Any tips from replacing a BL module in a PWD board?

    B.
     
  16. Steve Maller

    Steve Maller UAV Grief Counselor

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    What can you guys tell us about heat sinks? Is everybody using them? What kind? And how to install them?
     
  17. Josh Lambeth

    Josh Lambeth Well-Known Member

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    If it gets even remotely warm where you live (80*+) then heat sinks are a must for the 5D. In 90* temps here in Phoenix I was running right around 100*C on the BLs. Once I added the heatsinks I was running around 90*C. Once the temps went over 100*F here my BLs were in the 100*C range again WITH the heatsinks. If I hovered for more then about 5 seconds the temps were climbing even higher. I had one flight where I had a BL hit 113*C. I called it a day after that.

    Josh
     
  18. Ben Freedman

    Ben Freedman Member

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    I have them and will install them, but I'm now trying to figure out on a day with an ambient of 65 degrees, why this BL failed...

    Also, upon inspecting the board, it appears that the copper trace of BL#3 where it connects to one of the motor pigtails has started to lift. Is there any way to fix that?

    Yikes! It feels lie this board is a lemon!

    Ben
     
  19. Josh Lambeth

    Josh Lambeth Well-Known Member

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    Hmm.... Can you send a picture of that as well?

    Josh
     
  20. Ben Freedman

    Ben Freedman Member

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    Yup... Good news! The copper trace has now come completely off... I say good news, because it was on my shop table, and not up in the air!!!! :(

    I'll get a photo to you shortly...

    Best,

    Ben
     

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