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Draining Batteries Below 5%

Discussion in 'Inspire 1 Discussion' started by Lesmess, Aug 6, 2015.

  1. Lesmess

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    Hi,

    I'm trying to drain the battery down to less than 5% whilst either in the hover or on the ground. When she gets to 10, 11% she just lands and stops the motors. Not been an issue before as I just run the batteries down at home with the bird switched on and recording video. However DJI are now stating this should be done in one operation without switching the battery off. I only do this once every 10 battery charges.
    How do other folks do this full discharge thing.
     
  2. SultanGris

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    thought you were supposed to do it every 20 charges? I just leave it powered on after the motors quit working and go do something else for a while, it will shut itself off when it runs out of power in about 20 minutes or so depending on percent remaining when the motors stop. Mine seem to keep running at the lower percentages but they wont start if you shut them off and try to restart them. Im running a few versions behind on firmware though, maybe thats a change.
     
  3. Scotflieger

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    You have to manual counteract the I1 trying to land by keeping the throttle stick fully forward between 10 and 5% to keep it in the low hover or on the ground and stopping the motors from shutting down. You also need to cancel any automatic landing warnings.
    The DJI recommendation is to deep cycle the batteries every 10 to 20 flights. In the case of the latest FW (1.3.0.0) there has been a remodelling of the battery life logic (probably to avoid the sudden battery death problem) which can show a drop in the maximum power (mAh) and flight times after updating. The 100%-5% continuous discharge and recharge is the DJI recommended way of recalibrating the battery.
     
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  4. MickWalker

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    I only got mine down to around 9% during this stage of the firmware upgrade. Does this mean I should do it again?
     
  5. Scotflieger

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    Possibly. It took me 2 attempts on a couple of batteries to get the process right. It is important the discharge process from 100 to 5% is continuous for it to work. You can't stop and use a different method (ie. SPC4500 deep cycle) halfway through.
     
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  6. SultanGris

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    i thought you were supposed to drain it till it shuts itself off completely, 0%? did they change that recommendation?
     
  7. MickWalker

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    I know what I am doing this evening then - 8 batteries :(
     
  8. Scotflieger

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    You will find that the motors will cut at 5% no matter what you do. Then if your check the GO app the batteries will show anything from 5 to 0%. What you won't be able to do is switch them back on.
     
  9. MickWalker

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    Oh my motors cut off, and I was unable to power them back on - but Go did not say 5%, I think it was around 9%
     
  10. SultanGris

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    yea but i just leave the inspire powered on and it slowly drops to 0% and eventually shuts itself off. It says to do this in the manual that came with my inspire when i bought it in january. havent read anything about the drain to 5% so i was just wondering if they revised the draining till it shuts itself off recommendation to only 5% instead now?
     
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  11. Scotflieger

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    Please read the other answers I have given above. You need to keep the throttle up/forward to keep the motors from shutting down between 10 and 5%.
     
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  12. SultanGris

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    yup, thats my experience as well, if you just let them idle they auto shut off, slight power must be applied to keep them going on the ground without actually giving it enough to take off ideally.
     
  13. tassieflyer

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    How do you cancel any automatic landing warnings?
     
  14. Scotflieger

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    As you would normally. Pressing the CANCEL button (if it appears).
     
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  15. tassieflyer

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    Thanks for that. It's just I haven't flown to a situation where that warning comes on.
     
  16. Lesmess

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    It now just comes up with a Red Cross to clear
     
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  17. Loaderbull

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    The manual stated this for battery maintenance. Since the firmware 1.3 released yesterday, they updated the battery firmware and have said you need to re-cal the batteries due to this. As @Scotflieger said above. I believe all of this is in the firmware release notes...
     
  18. Batteryman1952

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    I think you guys are taking this 0% thing too far.m and causing your fuel gauge to be inaccurate. If it was my battery I would hover until the auto shut-off kicks in and call that a complete discharge 0%. I realize your fuel gauge is telling you that there is still 10% remaining in the battery but If your copter won't fly, the battery must be 0% right? Not 10%! Since this procedure is only being done only to recalibrate the fuel gauge so your controller can accurately report the state of charge during flight it will always be wrong if you drain the battery to 0 with a light bulb. Then from a battery life perspective, if you drain the battery to actual 0% with a light bulb or resistor you are actually causing damage to your expensive battery!
     
  19. The Editor

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    No you're not. 0% is a relative expression since all the Inspire packs contain a LVC protection.
    The same way your cell phone switches off at '0%' and does no harm to the battery, the same is true of the Inspire batteries. They are still over 3v per cell at cut off.
    The purpose is to recalibrate the fuel gauge which will be inaccurate after several cycles owing to the fact the internal resistance of the cells is increasing with usage.
    I light bulb to discharge is fine since it will take the pack down gently (1C or less) and the LVC will cut in to turn the pack off.
     
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  20. Batteryman1952

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    Ok fair enough but won't it still tell you that you have 10% remaining when the copter will no longer fly?Also Just beware that 1) every battery gets less cycles the deeper you cycle it and 2) the closer you go near actual 0% SOC for a multi-cell battery, the greater the chance that one of the cells may become "reversed" which does irreparable damage to that cell. BTW this is what can happen when you leave on your expensive 3 or 4 cell alkaline battery flash light until the light goes out. You open the flashlight only to find that one of the cells has "leaked" all over the inside. This is due to the fact that the weakest cell reached zero volts and then the other cells continue to discharge driving the weak cell into charging (i.e. The term "reversed"), generating hydrogen, bursting the safety vent and leaking electrolyte.