On getting the most out of a motor

I bought this Turnigy G15: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=56220

Spec.
Battery: 3~4 Cell /11.1~14.8V
RPM: 810kv
Max current: 42A 
No load current: 11V/1.5A
Internal resistance: 0.03 ohm

I ran a test at full speed fixed on the ground, and obtained the following graph:
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I notice the current only goes up to 32 Amps.  The spec says 42A.  Is there a way I can get more amps to the motor?

I have the following 4S 5200mAh battery: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=64434

Specs:
Minimum Capacity: 5200mAh
Configuration: 4S1P / 14.8V / 4Cell
Constant Discharge: 10C
Peak Discharge (10sec): 20C

So even at constant discharge it should be able to reach 52A, 104A at peak.

As for the ESC, this is the 50A Opto I have: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=81227

Specs:
Constant Current: 50A
Max Burst Current: 60A
Input Voltage: 7.4~22.2V (2~6S LiPoly)
BEC: OPTO
Output: 12V

Last the prop is a 11x7: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=20323

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  • ... so to "get most of it"  - you'll need to focus of thrust vs power , testing various timing settings and propellers.

    to get most thrust out of it, (regardless efficency) just up propeller pitch and/or voltage.   - the motor itself will work fine on 6S too, provided that the timing/load is ok.

  • And real max power often relates to cooling...  it's all  linked.

    as I mentioned, you won't see "(4*3.7V)=38.85A"  simply because it's not how it works.

    the voltage not "just connected", it's timed and PWM 'ed, how big current you'll see, is not about simple math. 

    And again; what you see is not necessarily real , even if your power module is calibrated, simply because it's not a linear and smooth load, it changes at very high speed. (every time motor changes phase, and also during one phase.)

  • What max current should I expect from a motor which spec says X Amps then?  Is there a rule of thumb?

    The power they indicate is 575W.  I don't know if that's the "max rated power" though.  Taking that, and a nominal charge for a 4S battery, that gives 575W/(4*3.7V)=38.85A.  Still above the 32A I see.

  • your understanding of this is just wrong. - do not expect max current to be "normal" , and measurable by such simple tools, it's the  current an phase can take, and it will/increases sharply when the coil nears saturation.

    this is not a simple , resistive load or a DC motor. you should rather focus at maximum rated power. (watts)

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