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Healthy Drones Telemetry

Discussion in 'Inspire 1 Discussion' started by RaptorMan, Jan 8, 2016.

  1. RaptorMan

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    OK, so I completed my first flight and uploaded it to Healthy Drones and among the data collected the thing that struck me was the battery temp. It was cold today, about 34F degrees, and at the start of the flight the battery was at about 57F degrees and by the end of the flight it had increased to 87F. Actually, the temp started at 57F and decreased to 55.7F before beginning to increase. I think that's due to the fact that the first 30 seconds of power on was compass calibration and that doesn't put much of a load on the batteries so the TB47 continued to cool off due to the cold air temps.

    So, even as cold as it was and with no pads on the battery the pack increased by about 31F in 8.5 minutes. I'd asked about this a few days ago but now that I have my I1 flying I'm able to see this for myself. So, it looks to me that so long as you keep the battery warm before flying and don't take a lot of time getting into the air the battery temp should be just fine once you're flying.

    Also in the Healthy Drones data was a log of warning messages and I had one just before takeoff warning me that the battery temp was below 15C and to warm the battery to 25C. If I'd started at 25C it's likely the battery temp would not have increased quite as much but still likely that the max temp would have been nearly 100F. I can see how flying in really hot weather could cause the battery temp to really climb -- what's the highest temp anyone's seen so far?


    Brian
     
  2. damoncooper

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    Specs say officially that ambient temp for flight can be -10C to +40C, but at 40C, the battery temp will be much higher of course
     
  3. RaptorMan

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    Yeah I'd guess if the air temp was 40C the battery would probably hit something like 70C or nearly 160F. Whereas in the winter time like it is now for those of us in the northern hemisphere we have to keep the batteries warm, if you're working in the summer when it's hot you'd want to chill the batteries. My take off temp today was 57F or less than 14C so I'd guess chilling the batteries to, say, 10C would be helpful in the summer.

    What's the hard limit for the new firmware? I was below 15C and it gave me a warning but let me fly so obviously 14C is OK but just how low before it won't let you fly?


    Brian
     
  4. Uptowndisco2

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    Strange thing is if temp below 15C is giving a warning message , DJI's own battery warmer is designed to only heat the battery up to 5C if it was so important the heater would or should be designed to bring the battery temp up to that 15C level ?
    I own the heater and the specifications are in the small instruction leaflet that comes in the heater package.
     
  5. RaptorMan

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    Yeah, that does seem kind of odd. I'd say that if you needed to heat the batteries at all then more like 25C-30C would be preferable. In the summer time it might be desirable to chill them to 15C-20C.


    Brian
     
  6. Scotflieger

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    @RaptorMan The latest I1 FW 1.6.0.40 has changed the way the battery power is managed in cold weather conditions (<15C). The nature of LiPo battery chemistry is that they are poor at delivering large amounts of power at low temperature. Excessive current draw can damage the battery and lead to a rapid drop in charge/voltage. This is now indicated by the increased visibility of the traffic light colours in the GO app battery page.

    You will get a warning in the GO app (2.4.4 or later) if the battery temperature is below 15C and the motors will not start. The battery needs to be warned before it can be used using the DJI Battery Heater or hand warmers. It is also recommended that the aircraft be held in a low hover until the battery temperature rises to 20C before any hard manoeuvres are attempted. The firmware also moderates the amount of power that can be drawn from the battery at lower temperatures reducing the rate of climb and forward speed. The effect is that you should see less battery cell traffic lights going amber and red.

    The advice is to only carry out moderate manoeuvres until the battery is up to full operating temperature (25-40C).
     
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