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I reproduced the drop voltage of death (with screenshots)

Discussion in 'General Discussion' started by Hercules_One, Apr 29, 2016.

  1. Hercules_One

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    Nothing new here, like this thread of huppe

    Tested batteries for fast dropping down in voltage

    But interesting to see the behaviour of the battery and voltages.
    I knew this would might happen, so I tested at 30 cm of ground. aprox 70% of batteries like one week stored.


    Firmware 1.4


    Before starting engines

    [​IMG]

    After seconds

    [​IMG]

    Voltages

    [​IMG]

    Then it got down to 2% in seconds and landed, something like 3.4 V.

    After hours of rest, interesting to see the voltage and the remaining percentage, not talking at all.

    [​IMG]

    Should I recharge these batteries normally, at 100% and fly like nothing happened?

    Thoughts?
     
  2. cougar

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    So are you saying that after battery has been sitting for a week and automatic discharge has set in, you went flying without charging to 100%?
     
  3. Hercules_One

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    As I said before, it was a test 30 cm or less off the ground.
     
  4. Dr. Ifly Drones

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    What cougar said. Your batteries were automatically discharging and you committed one of the cardinal sins of the RC world; letting charged batteries sit for days and then using them assuming they will maintain charge. Never fly more than 24 hours from finishing a charge.
     
    ted35 likes this.
  5. Hercules_One

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    Ok, lesson learned.
     
    Ragnar51 likes this.
  6. Dr. Ifly Drones

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    Don't take this as a dis or slap, just a fact of life we have all learned. I learned this lesson the hard way just like you but, like you also avoided disaster. Learn your craft, read the instruction manual and try to memorize it if you can. Hundreds of posts here that ask questions that are all answered in the OM.
     
  7. bluethundr

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    This statement should be placed just below commandment number X : Thou shall not covet
     
  8. ISP5557

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    I thought they fixed that issue in one of the last firmware updates?
     
  9. SanCap

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    The OP did not update the firmware.
     
  10. Hercules_One

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    I'm at 1.4, I don't know if there are further test with new firmwares.

    Which FW are the majority using here?
     
  11. DrMrdalj

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    This is direct evidence that percentages od batt. capacity are strongly aproximated and calculated by unreliable method. I know that such info in % is wellcomed by many hobby flyers, but I find it potentially missleading, so for Pro flying VOLTAGES are what really counts and measures. In years before "inteligent" multirotors, operator had to have deep understanding of battery and its cycles. It was and still is much safer to learn and monitor then to relly on "intelignet battery"...

    Therefore I am really disapointed by new design od GO App 2.7.2 and 2.8 where voltages are displayed in smaller letters, usualy white text on green box, so they are very hard to read - battery voltage should be one of the major display features, not the other way around...
     
    Peet05 and Hercules_One like this.
  12. Hercules_One

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    Completely agree with you.
    Actually, when I recharged them, when they was at the second light, they " jumped" to the fourth light in a second, hence the voltage was correcto and not the percentage.
    Also agree with new design, actually I would prefer a mini cell chart voltage in a córner, that would be really helpful. At least the block change colores from green to yellow and red.
     
  13. The Editor

    The Editor Moderator
    Staff Member

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    Voltage is not as accurate as mAh consumed. It is for this reason I have asked DJI R&D to look at a non volatile memory register within the batteries that will reset upon full charge and keep a count of the mAh used from the pack as it depletes.
    This method will be much more accurate/reliable than any useless 'intelligent' guess of capacity remaining based on state of charge.
    To be honest - I do not really take any notice of the percentage when I fly. I have been flying RC for so many years I am more interested in the voltage of the lowest cell under load and even if the % meter indicated 70% but I had a cell at say 3.3v I would be landing!!
     
  14. Hercules_One

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    Hi Editor,

    Do you have at least a vague idea why would the battery system come down from 3.98 to 3.42 volts under load in a matter of 20 seconds? Maybe the LiPo degradation over the lapse of a week? Bad software? I know I won't be doing this again, just to learn what might have happened here.
     
  15. ByronH

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    Would keeping your batteries on a charging hub prevent charge loss over a period of days?
     
  16. Fastrack

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    It's bad to keep lipo batteries fully charged. Before I bought the inspire I would "storage charge" or discharge if I was not flying within 24 hours. Storage voltage is 3.85v/cell.

    With the inspire batteries you have a choice of 1-10 days before the discharge starts. Which as I understand it takes 2 days. Pressing the on button once resets the 1-10 counter. Also I believe leaving it on the hub also stops the counter.

    I personally would use 1 day. But I'm thinking of looking into a discharge method. I've seen a few mentioned on the board.

    Newest firmware does not have this problem described in this topic.

    Ben
     
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  17. Kevin Hancox

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  18. Frank508

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    This is a well documented characteristic of the DJI batteries. Once the batteries have entered the self-discharge cycle the only safe thing to do is to recharge to full. I haven't tried it with the new software, but I have a couple of batteries that have diischarged so I'll try it and see what happens, at 6 inches, of course.