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Battery voltage crashes answers

Discussion in 'Pro/Adv Discussion' started by Wibble, Dec 24, 2015.

  1. Wibble

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    Ok so after much reading is the following an accurate summing up?

    1. Voltage drops below a certain figure then it just shuts off to prevent damage to the cells resulting in a crash.

    2. Sudden acceleration on a low battery can cause a momentary voltage drop. Again leading to a crash

    3. Cold weather will make the problem worse.

    4. New update limits power to prevent this happening

    IF all the above are true wouldn't it be better for DJI to over ride battery shut off?
     
  2. N017RW

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    Voltage sag, regardless of cause, drops below regulation drop-out value.
    (This may be a confluence of many factors.)

    Imbedded uP resets in flight.

    Flight control lost.

    Gravity does what gravity does.
     
  3. tcope

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    So far it appears that this is only an issue with the P3 and it appears to only be a real issue when the batteries are cold. The best answer is to correct the issue and still allow the battery to turn off when it's critically low. DJI thinks that they have done this.
     
  4. RedHotPoker

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    They know what's best for your drone. & We don't know.
    I live in a cold country, so Definately looking forward to this cold flight battery update. ;-)

    RedHotPoker
     
  5. msinger

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    True, but how would DJI educate people to stop flying it like they stole it when the battery voltage is low? It might make the best sense to configure the Phantom to control the throttle when needed, but have a setting that would allow that throttling to be turned off. Kind of like manual mode in the P2V+.
     
  6. tcope

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    I don't think my post was 100% clear. My remark is that I don't know DJI doing anything else is a better solution. I think what they did (if it works correctly) is the best of both worlds.

    Also, we don't know for sure what all was changed. I would agree that another change that should be made is to not allow the battery to turn off if the drone is reporting a home point... or something along those lines. I'm ruling out the motors being on and its possible someone would be running the motors to drain the battery and, for example, not have the props on. There should be several ways to do this. But as I mentioned, I don't know for sure that they did not make this change.
     
  7. msinger

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    It seems odd that it's shutting off and not getting to the critical low battery stage first. Perhaps the voltage drop is so drastic that it doesn't have time to kick in.
     
  8. kphantom

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    I agree, it would be better for DJI to do something different. Why would they allow a battery to shut off while in flight? This does not make sense.
     
  9. tcope

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    I think it's been shown that it does get to this critical state. Under cold temps and full throttle it was. So the batteries shut off. This is why DJI has now limited full throttle when the batteries are cooler.

    I know that I'll still be flying for a bit before getting anywhere near full throttle. Having your P3 fall 40' onto pavement will have this affect.
     
  10. msinger

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    Per the Phantom manual, at the critical low battery level, the Phantom is supposed to auto land itself. It seems that function is being completely bypassed sometimes.
     
    dirtybum likes this.
  11. tcope

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    Two different measurements. Critical is being used to describe many things. Critical battery when it comes to flying is around 20% or near 3.2v. Critical when it comes to a killed battery might be closer to 2% or 2.xv.
     
  12. msinger

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    I'm only referring to the "critical low" battery level -- as described in the Phantom manual. Critical in general could translate into a vast array of things.