About Batteries, their weight, capacity, etc...
I ordered some batteries online at Banggood and they were all 3S batteries, meaning 11.1V, 1500mAh.
I was surprise to see how different they looked. The main difference was the weight. The heaviest was 136grams and the lightest was just 106grams.
Because energy in a battery is proportional to the volume, how can you have the same capacity of 1500mAh and 11.1V if you have such a different weight.
So I looked on Wikipedia, and found that the LiPo technology has an energy density of 100 to 265Wh/kg which make a ratio of 265% difference from one battery to the other.
My conclusion here was that in that case, this difference of 35% in weight was still less than the 265% in energy density so I decided to see how they behave in real life.