Lipo maintenance questions

Discussion in 'Electronics' started by Dave King, Apr 4, 2013.

  1. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Josh:

    Thanks for the information. I'll be sure that Abe gets the message. :)

    Andy.
     
  2. Joe Azzarelli

    Joe Azzarelli Active Member

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    Thx Josh. The question mark you see floating above my head is... Measured with no load below 3v is a problem we know, but is an excursion below 3v under load ( while flying ) a bad thing when, after landing, it now measures 3.3 ~ 3.4. (?)
    I am not trying to fly to the bleeding edge but I also do not want to set it higher than needed and MK decides to land before I am quite ready.

    These are great to attach to the batt during flight and are very loud but unfortunately there is no telemetry.

    Joe
     
  3. Gary Haynes

    Gary Haynes Administrator
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    Joe if you were to always plan to fly to say 3.1 volts per cell, what are you going to do in the case of the unexpected like a wind coming up, a group of kids starts playing in the landing area, etc? What fuel safety margin do you need?

    For airplanes etc the FAA has pretty solid guidelines on the amount of minimum fuel required. Yet every year airplanes have forced landings for running out of fuel. Some of the Zippy batteries I have used, well let's just say when they get low that the voltage starts dropping pretty quickly towards the end.
     
  4. Joe Azzarelli

    Joe Azzarelli Active Member

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    Gary
    You are misunderstanding me. Actually it is your points that I have in mind...
    I set my warning to 3.3v/cell on the telemetry so I start heading home when I get the warning. So if I get to where I need to land and THEN I get an unexpected wind or group of kids...I do not want the MK electronics landing FOR ME when I know I still have some reserve time! In other words I want to know how much maximum reserve I have so it is not a panic if there is some trouble between warning and landing.

    The fast drop off of voltage is not only a Zippy issue. It is why I am convinced for mission-centered flying two batteries are much better. You give up some total flight time but the drop off is more gradual and there is less stress on the batteries when taking them down to empty.

    Joe
     
  5. Gary Haynes

    Gary Haynes Administrator
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    Yep misread it. Personally I have my warning set at 14.4 (3.6v). That gets me to about 30% remaining and I don't like going below 20%. And while it might seem high if I were flying for someone else I would simply tell them in advance what my planned max flight times are going to be. Reminds me of Clint Eastwood 'A man's got to know his copter limitations. Do you feel lucky?'
     
  6. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I also use 14.4v. When I'm just flying for practice or testing, I'll bring the bird back and hover/fly near to home, just to take it down to 14.0v -- more to give me a sense of how much reserve I really have. I look at the GPX file to get flight times for 14.4 and 14.0v

    Andy.
     
  7. Joe Azzarelli

    Joe Azzarelli Active Member

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    well, punk, do ya??! :D
    I think I will up my warning a little as well. For me it isn't the copters limitations - its mine!
     
  8. Gary Haynes

    Gary Haynes Administrator
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    Yeah but Joe are you flying the MAGNUM version, the most POWERFUL OCTOCOPTER IN THE WORLD????
     
  9. Joe Azzarelli

    Joe Azzarelli Active Member

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    ...YES and it will blow your leaves CLEAN OFF!
     
  10. Ryan J. Rowe

    Ryan J. Rowe Member

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    Yep, Mine just cracked and melted enough for me to notice it. As I inspected it closer there were cracks under the shrink wrap. Who knows how long they've been there. Not to mention that I had been noticing that it was taking less force to connect/disconnect the battery. Enough that I started taping the connection just for safety. Just ordered some new ones with extras for spares...
     

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