<p>The 80 amps on the ESC is its <em>rated</em> (maximum) current not what it consumes. The maximum current draw of the motor should be less than the <em>rated</em> current of the ESC. Otherwise the ESC will heat up and stop working.  30 amps sitting on the ground might be reasonable as the motors are spinning but not providing any lift.</p>

CC BY-SA 4.0
2021-08-18T08:16:59.870Z
"but not providing any lift" doesn't make sense - the motor will be working hardest when the plane is static and will draw less power when the plane is moving, as the air arriving at the prop will already be moving. I agree with everything else though.
Robin Bennett
CC BY-SA 4.0
2021-08-18T13:12:49.450Z
You are right, I was assuming a copter. However the OP said ground test so no lift in any case.
Kevin
CC BY-SA 4.0
2021-08-17T13:23:22.153Z
2021-08-17T13:23:22.153Z
Kevin
<p>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).</p>
<p>Any ideas on what's behind this?</p>

CC BY-SA 4.0
2021-06-28T11:27:29.367Z
What propeller do you use? How do you determined the expected power?
Arcaniaco
CC BY-SA 4.0
2021-06-28T15:25:53.107Z
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
Brydon Gibson
CC BY-SA 4.0
2021-06-29T07:59:07.480Z
SunnySky's data predicts 72amps with a DXL14*8 at 16.8v   
https://sunnyskyusa.com/products/sunnysky-x3520-brushless-motor
About the only mistake you can make is the wrong size of prop.
Robin Bennett
CC BY-SA 4.0
2021-06-29T12:57:51.123Z
@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.
Arcaniaco
<esc>
Why is the ESC not giving enough current for my propeller?
254 Labdawan Putra Karsa
# Why is the ESC not giving enough current for my propeller?

(Asked by: username_0 on 2021-06-26)

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?

**Tags:** esc

> **Comments:**
> **username_1**: What propeller do you use? How do you determined the expected power?  
> **username_2**: 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  
> **username_3**: SunnySky's data predicts 72amps with a DXL14*8 at 16.8v    https://sunnyskyusa.com/products/sunnysky-x3520-brushless-motor About the only mistake you can make is the wrong size of prop.  
> **username_1**: @username_0 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.  

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## 1 answers

### Answer by username_4 on 2021-08-17. Score: 3

The 80 amps on the ESC is its *rated* (maximum) current not what it consumes. The maximum current draw of the motor should be less than the *rated* current of the ESC. Otherwise the ESC will heat up and stop working. 30 amps sitting on the ground might be reasonable as the motors are spinning but not providing any lift.

> **Comments:**
> **username_3**: "but not providing any lift" doesn't make sense - the motor will be working hardest when the plane is static and will draw less power when the plane is moving, as the air arriving at the prop will already be moving. I agree with everything else though.  
> **username_4**: You are right, I was assuming a copter. However the OP said ground test so no lift in any case.  

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