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P3 & Snow?

Discussion in 'Pro/Adv Discussion' started by pilot ss, Aug 20, 2016.

  1. pilot ss

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    I know that there are already a couple of threads regarding snow and phantoms.

    I am heading to the snow next week for some boarding, and am contemplating whether or not to take the P3.

    I would NOT be flying whilst snowing, and would only be bringing it out once it had stopped snowing. Looking at the forecast, temps shouldn't be getting lower the -5 degrees Celsius.

    Is it advisable to not fly P3's when it is this cold? Moisture? What are the risks?
    I obviously don't want to risk hurting the P3 short or long term

    Cheers.
     
  2. GuernseyZoo

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  3. Dronason

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    You will have to wait long time during warming time of P3 before flying. Try to calibrate the IMU at a very cold temperature.
    Then you are back from cold area. You can recalibrate the IMU for more usual temperature.
    Should give amazing video / pictures if there is some sun.
     
  4. Mark The Droner

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    -5C may be a bit colder than the temp range DJI would recommend - check your manual. Still - many have reported flying in that kind of cold and much colder with no problems. IMO, most important thing is to start with a WARM battery.
     
  5. matti

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    Use warm batteries before take-off and let the AC hover low a minute or two before going higher. Fly gently and watch the lowest voltage -- consider landing your Phantom when (or before) the first battery cell reaches 3.4V.

    Whenever you launch with a battery which is not fully charged, take care to fly gently; do not apply full throttle up & out, and keep an eye on the voltage indicator. Be extra careful in cold temperatures. The voltage sag that happens with aggressive flying in cold weather, led to some P3's falling out of the sky. (i.e the battery voltage would briefly sag to 3.3V on an aggressive move, the FW (v1.5?) would erroneously interpret that as 3.0V instead, and shut the motors down.)

    If you have cold batteries, the last thing you want to do is increase propulsion. LIPO batteries need to be warm for best performance. DJI suggests allowing a warm up period before lifting off. It won't let you fly without the battery reaching 15°C first.
     
  6. 4wd

    4wd

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    The batteries aren't happy at much below 15C, but once in use the internal heat generated is more than sufficient probably even below -10
    Ideally you want the batteries warm from indoors or vehicle and if not starting immediately an inside pocket would be advisable.
    When you take off give it a minute or two hovering to warm up before doing any aggressive moves.
     
  7. pilot ss

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    What is the best method to warm the battery prior to flying? Come to think of it I wouldn't be flying in anything less then 0 degrees Celsius.


    Sent from my iPhone using PhantomPilots mobile app
     
  8. Dronason

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    Use the DJI heater. You can also try to keep close to you skin within your jacket.
    Be sure to let it warm at start by leaving is hovering a minute or 2. You can check the battery temperature in the GO app.
    Capture.PNG
     
  9. Avocet

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    Heating batteries ... if you have to travel on foot with your craft any distances, obtain a few of those hand warmer throwaways and a small towel.. wrap your battery up partially in the towel and wrap the activated hand warmer in the towel in or on proximity of the battery and stuff it into a pocket, or somewhere else that makes thermal sense. :)

    (Is that your battery or are you just glad to see me!?)
     
    fastsmiles and Dronason like this.
  10. pilot ss

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    Unfortunately I have left it too late to purchase the battery warmer, as I would have to order online and I am leaving in 2 days. I would assume that inside the temp will be around 15degrees Celsius, so I would have thought that the battery would be warm enough from being inside to just use straight up (put battery in P3, then take outside where temps are much cooler. What temp does the battery need to be before taking off? Will it not allow take off if the battery is not optimal temp or do you run the risk of it falling out of the sky because it is not warm enough?
    Cheers.


    Sent from my iPhone using PhantomPilots mobile app
     
  11. WetDog

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    Depends on your firmware. After 1.6 DJI started putting warnings up if it was too cold. Those warnings tended to be rather paranoid so if you see them, use the methods that everyone has been telling you about to warm up the batteries rather than staying in the bar.

    Warming the batteries isn't hard. The big deal is realizing that you might have half the battery capacity that you normally have. Be conservative.
     
  12. Vertigo

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    Im not sure I agree. Low temperatures will decrease capacity, that much is certain. But afaik, low temps are not harmful to the battery as long as the (increased) voltage sag doesnt pull them below ~3.3V per cell. If you keep the battery load to a minimum (hovering) in a really cold environment, my guess is that you risk that the battery cools below what you started with.

    So rather than hovering for 2 minutes, I wonder if you shouldnt do the exact opposite, while no load voltages are still high, warm the battery by increasing its load, ie, climb/fly aggressively. This is assuming you start with a reasonably warm (15C) battery.
     
  13. happydays

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    Watch the camera lens doesn't mist up.
     
  14. Dronason

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    If the battery is reasonably warm, there should be not that much issue in any case. I should have maybe put a OR between the 2 parts, but it is also better to be on safe side.
    At lower temperature the battery internal resistance will increase and the risk to come to a low voltage situation. DJI played with its firmware about that to avoid that the P3 power down at low temperature. Trying to ask for high current if the battery is really cold is calling for risks. (see http://www.eastbayrc.org/TimTips/TimsTips_LowTempLiPoPerformance.htm).
    So the battery need to be either heated before placed in the P3 (better IMO) or after the long warming by the P3 launched and hover for a few time so that it self heat to reasonable temperature.
     
  15. Vertigo

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    AFAIk, the only risk is voltage sagging, which is unlikely to result in <3.3V with a fully charged battery, even if its cold. The chart you linked does show this, but then it also shows the same battery dipping below 3.3V/cell at 25°C temperature almost immediately, so his battery is terrible / not able to sustain 10C discharge rate regardless of temperature.

    Besides, I thought you couldnt take off if the battery was below 15°C ? Unless Im wrong in that, if you're able to take off at all, I see no reason to hover for several minutes.
     
  16. pilot ss

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    Ok will try warming the battery up inside, which should work as the fire is constantly on, and temps are much warmer then outside. Would it be best to start the P3 inside and let it warm up, shut the motors down, walk out side with it and start the motors up and proceed to use the P3? Or would the drop in battery from the start up inside be too great to take off once outside?


    Sent from my iPhone using PhantomPilots mobile app
     
  17. Dronason

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    I think it will be efficient but it depend how cold it will be outside and how much time till you are ready to fly.
    After a flight, usually the battery stay warm (or even hot) for a while, so inside the P3 it should stay warm.
    The P3 too, the warm up of a second flight is usually much shorter. But the battery will really warm only when the motors can be started.
    In any case, you can view the live temperature of the battery and check it inside and outside when you are ready to fly.