# Weight vs Battery life..... Thank you for making this possible

Brief introduction

Hello everyone,

What my experiment is

Oh yeah, before you look at my data let me quickly explain what the experiment actually was.

I attached weights to my quadcopter and measure how weight affects the battery life of a quadcopter. (the quadcopter I used was the Parrot AR Drone 2.0) The reason I did this, was because I wanted to see the effect that cameras have on the battery life of a quadcopter. The main factor that they affect is battery life, because they are heavy.

Here is my data

 Weight added (g) Battery life (s) 0 546.6 16 517.3 28 501.0 36 482.3 54 461.3 78 449.6 86 393.3 94 364.3 106 337.6

Conclusion

As we can see, battery life is affected by weight, however not by that much. To give context to this experiment, and make it relevant to this community, a gopro (a favored camera by many on this site, from my experience) weighs in at 130 grams.

Two things to note, First, more weight could not be added without losing control of the quadcopter This was because all the tests were done at the lowest setting, so that clear trends in the data  could be found, as well as to keep consistency throughout. The drone could probably carry more, however this would significantly reduce the battery life. Secondly, the Parrot Ar Drone 2.0 power edition only weighs 380g, which makes it a mid league quadcopter, not the best suited to carry a camera in the first place.

Views: 4566

Comment by Ben on March 10, 2016 at 7:21am

It could be interesting also to measure battery weight vs flight time, because there should be an optimal value for optimizing flight time. (small battery = shorter flight time, large battery = shorter flight time too because of the added weight)

Comment by Bart Theys on March 10, 2016 at 7:52am

Theoretically , 66% of the total weight should be battery. In other words: multiply your drone's weight without battery by two and take this amount of battery. In practice, 50% will do because most of the times your propulsion system will not be able to handle this large weight. I would be interested to see someone trying this :)

Comment by Cala on March 10, 2016 at 8:25am

Good Kieran: take in mind that your settings changes with different weight, check your temperature components with higher weights not to damage them, different setups type affect in different proportion the added weight; Eg one test I did with my quad, the second equal battery added give me 50% (not 100) more flying time that the first one for reason that Ben explain.

T3
Comment by Ted Van Slyck on March 10, 2016 at 8:55am
@Bart: where did that %66 figure come from? Not contending it, just curious.
Comment by Bart Theys on March 11, 2016 at 1:33am

@Ted: required power scales to the power 3/2 with the total weight, available energy scales with the mass of added battery. With some boring math hocus pocus you'll end up with a battery that weight twice your empty mass. Perhaps I can write it out and make a post about it later :)

Comment by Hellcat74 on March 11, 2016 at 2:18am

Hi there, as an aero engineer myself I like your approach. Don't get bogged down with math just yet, just look at the data. First question is to ask how accurate your test is, i.e. how do you accurately measure battery life? At what point is it depleated?

Also look at your data points. Only 9 of them. Not so bad but what is happening to that outlier at 80g? Is that a true value or a "blip"? Try increasing your number of test points. If you have access to a statistics package like MiniTab then that will help design a good test for you. Have fun.

T3
Comment by Ted Van Slyck on March 11, 2016 at 9:56am
@Bart, I would love to read a blog post about the math you are outlining. I hope you write it.

MR60
Comment by Hugues on March 12, 2016 at 12:16am

I do not know where the 66% rule comes from but I can confirm my 1h15 long quadcopter flight had this battery/frame weight proportion. Would be interesting to model the maths behind it.

Comment by John Rambo on March 14, 2016 at 1:28am

I was always wondering why it is recommended to hover at ~50% max. throttle? Also, I was always wondering why people are checking max. thrust for evaluating max. lift capability? Propeller/motor has a max. efficiency at ~20% of its max. thrust. So, running a test in 15%-25% of max. thrust range, might end-up in rather surprising results, where adding extra weight might not decrease flight time at all, as you'll be climbing the efficiency curve.

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