# Why is the ESC not giving enough current for my propeller?

So I have a Hobbywing Skywalker 80 amp ESC and Sunnysky X3520-720 that I just did a ground test with a power meter. Results gave only about 31 amps at 16.3V which is way under what I was expected (around 60-80 amps).

Any ideas on what's behind this?

• What propeller do you use? How do you determined the expected power? Jun 28 at 11:27
• 720kv on 4S with (I'm guessing) somewhere around a 15" prop, 31 amps seems like a reasonable (maybe slightly low) current draw. Note that's 16 * 31 = ~500 watts or 2/3 of a horsepower Jun 28 at 15:25
• SunnySky's data predicts 72amps with a DXL14*8 at 16.8v sunnyskyusa.com/products/sunnysky-x3520-brushless-motor About the only mistake you can make is the wrong size of prop. Jun 29 at 7:59
• @254 Labdawan Putra Karsa The relationship between different thrusters are not straightforward, as you have to consider their efficiency. The efficiency of a propeller depends on the speed (in this case the rpm), so you cannot make this direct relationship, but you must analyze the propeller efficiency data and see in which region it will work to be able to estimate the consumed power. Jun 29 at 12:57