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Safe voltage for flying?

Discussion in 'Pro/Adv Discussion' started by davestern2, Dec 16, 2015.

  1. davestern2

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    So with all the talk of drones dropping and all of the discussion around batteries, what is the voltage level below which I should not fly? E.g. approximately when do I want to have landed so that I am not at great risk for the p3p shutting down in mid air?

    I would think the voltage supplied is not constant, e.g. if I'm putting less demand on the battery, the voltage may creep back up, only to drop when I draw more power (amps), but is there a range which would be good to know that I really need to have the drone on the ground by that time?

    Sent from my SM-N920V using Tapatalk
     
  2. msinger

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  3. alokbhargava

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    Don't worry, charge the batteries to 100% before flight (say last 12 hrs) and set the 30% low voltage alarm. Start defending and landing as you hear lithe alarm.
     
  4. Oso

    Oso

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    Just in case you haven't yet seen DJI's recent email regarding batteries.

    Flying DJI aircraft in winter can be fun, but we have heard that some of our users have experienced issues when flying in cold weather. Did you know that as the temperature drops, so does the performance of the LiPo battery inside your aircraft? Read on to find out how to look after your battery and keep yourself in the air.

    The Science

    LiPo, or Lithium Polymer batteries drain faster the colder they get because the chemical reactions that they use to create electricity are slowed. This starts to occur at temperatures lower than 59°F (15°C) and is a known issue of all LiPo batteries.

    At high altitudes where air pressure is low, motors on an aircraft have to spin faster to produce enough lift, meaning even more power is needed, in turn accelerating battery drain.

    What this Means

    In extreme cases, a battery could drain below 3V, causing reduced thrust or even battery shutoff due to over-discharge protection systems designed to keep your battery healthy.

    Hot Tips for Beating the Cold

    1. Make sure batteries are fully charged before each flight.
    2. Warm batteries to 77°F (25°C) or more before flight. We recommend using a battery heater.
    3. Hover the aircraft for around a minute to allow the battery to warm up.
    4. Turn on “Show Voltage on Main Screen" on the "Aircraft Battery" page of the DJI Go app. Do not continue flying if battery voltage drops below 3.2V.
     
  5. davestern2

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    Thanks... great info.. Was aware of some and learned a bunch.. Much appreciated. That long thread is excellent.

    Sent from my SM-N920V using Tapatalk
     
  6. Mark The Droner

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    Thought I'd share my battery story here real quick.

    I thought the lights were acting funny the night before, so yesterday morning I wanted to hover my P2V and watch the lights. No big deal. Just hover for a couple mins. So I grabbed what appeared to be my most charged battery which had 2 solid green lights on it and went outside (this battery hadn't been used in several months and was in storage charge, but did have two solid green lights).

    Since I was just hovering I didn't use an app or the mobile device.

    Turned it on and the lights were fine. Watched the satellites go 4, 5, 6, 7.... watched the compass direction lock, home point lock. Everything seems fine. Started the motors. And as it's sitting there on the ground with the props just starting to spin in idle, the lights all go out. All of them. No lights. Is that right? I'm not even sure. Is it possible I've never noticed this? I use Naza M. Sticks are centered. Both S switches are up. Props idling. No lights.

    Hmm. So I launch to see what happens. The lights go on and everything seems fine. It hovers perfectly although it does tend to rise a fall a bit but it's kinda windy out.

    I'm watching it as it hovers in front of me and I can see the battery now has the 1st light solid and the 2nd light blinking. Okay. Less than 50%. No biggy. I watch it some more while it deals with the wind.

    And within about 30 secs, the taillights are flashing RED. What?

    I look again at the battery while it's hovering in front of me. Now it's only got ONE green light and it's blinking! Less than 12%! Already? In less than a minute? How can this be?

    Well I better land it. As I begin to land it, it starts going UP. No no no. I plunged the left stick DOWN and thankfully it did come down to a few inches from the ground and then in a bit of a panic I CSC'd so it wouldn't go up again and the craft dropped a couple inches and tipped and the motors stopped. No damage.

    Went inside and checked the battery. It was at 11%. The cells were all BALANCED (which I think is pretty good for a battery at 11%). Lifetime percentage is 93%,

    Moral of the story: ALWAYS ALWAYS ALWAYS BEGIN FLIGHT WITH A FULLY CHARGED BATTERY.
     
    JonEQuest likes this.