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Is there a certain speed/throttle position for best battery efficiency

Discussion in 'Pro/Adv Discussion' started by fastfed, Sep 2, 2016.

  1. fastfed

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    For example, my car a TDI diesel gets the best MPG at about 50-55mph.

    taking wind completely out of the situation
    Going out and doing long distant runs , I usually just keep it in GPS mode and go full throttle out and back.

    I understand that with a 4 motor drone like this, going full speed doesn't always mean its using as much power as a single engine craft, the drone is already spinning its motors full speed to keep it up and I assume full throttle forward would increase the back motors and decrease a little on the front motors to create the tilt.

    I have no idea how the efficiency works on these things. Anyone do a test before? Say going half throttle rather then full throttle? less distance over time=more battery at end run?

    What do the distant breakers run at? full throttle?
     
  2. Mocho

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    I've done some testing but have not tested extensively, however from my experience it seems that with the P3P 10 m/s is optimal.
    Which is likely why DJI set the RTH speed at 10 m/s.
     
  3. N017RW

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    Mocho's logic is sound regarding the RTH speed.

    Lots of discussions here in the past but an experiment is just too complicated to due to so many variables for a definitive answer.
     
  4. mikesmiley

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  5. fastfed

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  6. flyNfrank

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    I just happen to be working on a project that shows how the newer battery firmware eats way more power then the older battery firmware. Anyway, here is a recent flight that you see 2 lines on the graph. If you look closely, you will the purple line represent Amps. The other greenish colored line is the Forward & Back Stick input.

    You can see the first 3/4ths of the graph I was running the stick near 1/2 input. The Purple shows the amount of Amps used during that process. A few spots after the 3/4 point you can see that I increased the Stick input to all the way Up, or Max depending how you reference it. And you can also see how the Amps raised up more by applying more power.

    I was a little surprised I could keep the Amp demand low by running 1/2 Stick input. (I need to look for a long RTH data and see what kind of amps were used there as well)

    I have always been told one important factor when it comes to efficiency, is by keeping the battery as close as you can to 100 degree temp. Btw, that's happens to be another one I'm working on as well. It consist of getting more air to the current battery bay setup.


    1half.jpg
     
  7. With The Birds

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    Optimum speed is 14ms for max range, ie pretty much flat out.

    long range drone DJI Phantom 3 professional

    Max efficiency is likely a lot less. Flynfrank's findings are interesting however it might be that to ultimately know what max efficiency is we would need to consider actual thrust delivered by the prop across the full range of power input to the motor.
     
  8. flyNfrank

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    The problem with thrust per prop is we don't current have that data in that manner. That was however a good mention though. The only possible thing that comes to me is, set a waypoint for a flight and measure the flight pitch and roll throughout the flight and adjust for it in the end. Btw, the DatCon has a way of measuring thrust but I'm pretty sure it only applies to which is the leading prop.
     
  9. mikesmiley

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    tl;dr

    People make this harder than it is. Somewhere around 31 mph is very close to being ideal.
     
  10. With The Birds

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    What do you know, thats pretty much bang on the nocker (just a smidgen under) the 14ms depicted in the article I reposred above..... for maximum flight distance on a battery. Its not what the OP asked though. Knowing throttle positiin for best battery efficiency is a different problem. One I dont understand the practical relavence of but its a seperate question none the less.
     
  11. mikesmiley

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    It's not what he asked? I could swear he was asking how fast gets one the most distance.
     
  12. With The Birds

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    The qusetion was is there a best throttle position for best battery efficiency....
     
  13. mikesmiley

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    "Is there a certain speed/throttle position for best battery efficiency" was the question. Since we all know that all other things being equal, throttle position dictates speed, I think you're deliberately missing the point.
     
  14. Multicoptertec

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    Efficiency is the keyword here indeed. To determine the answer to the OPs question would require testing under controlled conditions. There is most likely a battery amp/hour draw ideal scenario, and if we knew that, surely we could eek out a few more minutes of flight time.


    Sent from my iPad using PhantomPilots
     
  15. rocketflyer

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    Ultimately the measure of battery efficiency is how far the quad can travel on a charge (environmental factors being equal). IMO it is interesting to know if there is an optimal speed for max distance but ultimately not hugely useful as tail/head/crosswinds would have a greater impact.
     
  16. Multicoptertec

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    But it would be useful to know that. Forget the bird, motors, wind, etc for a minute. Let's just apply a given load to the battery, and time how long the battery will last. Then vary this load, and chart the times. The battery doesn't care or know if it's powering a quadcopter or an Energizer bunny.


    Sent from my iPad using PhantomPilots
     
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  17. With The Birds

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    On the contrary, my intent is in assiting fastfed with his question. In a seperate thread he opened yesterday he was concerned about "safe" maximum speed and the battery cutting out in flight if attenptimg to fly too fast. 14ms (as you said close to 31mph) gives maximum range. Its unquestionably one, and for most a very important, measute of overall AC efficiency. It is perhaps, and probably not, an indication of best battery efficiency. Cycle count, overall service life, cell balance, internal resistance and other factors will be more relavent measures here in determining the optimal load applied to the pack in flight.
     
  18. PVFlyer

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    FPV Camera app comes with a battery consumption meter as stated FPV Camera

    • Battery Consumption (Camera): Toggle On/Off Battery Consumption to show/hide real-time mAh/km (Metric) or mAh/mi (Imperial) in Battery Meter upon takeoff for optimizing economy cruise speed. It's similar to fuel economy (such as MPG or Litres/100km) of a car. The lower the value, the better battery consumption economy. When hovering with zero travel distance, battery consumption is the worst 9999 mAh/km.

    This is designed for those long range junkie who need to fly the longest range per battery and squeeze all the performance of their gears. Experienced pilots know maximum pitch forward joystick (the highest speed) might not be the best battery economy, especially in windy condition.
     
  19. flyNfrank

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    One thing you are forgetting to mention,....the details you are giving is based on a standard P3 oem battery. Btw, a Coca~Cola will just fine.