Question: CDROM Brushless on PICO Stick-F

[JYZoom]

Hi,
Got an cdrom brushless from rotor, it say outrunner 1500KVA. http://shop.rotor.com.sg/show-detail.asp?prodid={06B187C0-F03A-45A8-9D1F-88EAC27CC5A7}

I use prop 0843, Hobbywing 18A ESC with:

1) 730mah TP 2S: When I go full throttle, it will cut off with current up to 9A-10A.

2) 2100 TP 2S: I can go full throttle without cutoff with current only at 5A+.

Why the current is so different using 730mah and 2100mah TP? I attribute the cut off using 730mah is the battery C rating at 13C continuous for 730mah compare to 15C for 2100mah.

Another observation is when using cdrom brushless, the startup is not smooth and you need to full throttle to get the prop to spin properly, then the throttle input will be linear with stick input. Is this normal ?

Jonathan

[collectivepitch]

To make the throttle linear,
Try programming your esc throttle range

the hobbywing 18esc can program throttle range this way:
1) max throttle on tx
2) supply power to esc
3) wait for a beep
4) move throttle to minimum position
and
5) wait for 2 beep and music

[collectivepitch]

it need to be done once only if you do not change the esc or motor combination

[JYZoom]

done

collectivepitch,

Tks for your note. The end points was done as you describe.
The only difference is the battery being used.

Jonathan

[freeman]

Hi,
Got an cdrom brushless from rotor, it say outrunner 1500KVA. http://shop.rotor.com.sg/show-detail.asp?prodid={06B187C0-F03A-45A8-9D1F-88EAC27CC5A7}

I use prop 0843, Hobbywing 18A ESC with:

1) 730mah TP 2S: When I go full throttle, it will cut off with current up to 9A-10A.

2) 2100 TP 2S: I can go full throttle without cutoff with current only at 5A+.

Why the current is so different using 730mah and 2100mah TP? I attribute the cut off using 730mah is the battery C rating at 13C continuous for 730mah compare to 15C for 2100mah.

Another observation is when using cdrom brushless, the startup is not smooth and you need to full throttle to get the prop to spin properly, then the throttle input will be linear with stick input. Is this normal ?

Jonathan

Hi,

Got the same stuff from rotor. Got the same problem as you mentioned. So what is the problems....

Problem No 1
What I found out was the winding in the stators were not balanced. i.e. Some with 12 turns some with 10 turns.

Problem No 2
The magnet was not strong enough to spin anything useful.

Brought it up to rotor and the answer was not satisfactory...So what I did was re-wind the motor and change the magnet. I got the wire and magnet from gobrushless.com.

Cheers

Happy Flying.

[JYZoom]

tks

Freeman,

Tks for your response. What size plane and prop will you using?

JOnathan

Hi,

Got the same stuff from rotor. Got the same problem as you mentioned. So what is the problems....

Problem No 1
What I found out was the winding in the stators were not balanced. i.e. Some with 12 turns some with 10 turns.

Problem No 2
The magnet was not strong enough to spin anything useful.

Brought it up to rotor and the answer was not satisfactory...So what I did was re-wind the motor and change the magnet. I got the wire and magnet from gobrushless.com.

Cheers

Happy Flying.

[collectivepitch]

I use prop 0843, Hobbywing 18A ESC with:

1) 730mah TP 2S: When I go full throttle, it will cut off with current up to 9A-10A.

2) 2100 TP 2S: I can go full throttle without cutoff with current only at 5A+.

Why the current is so different using 730mah and 2100mah TP? I attribute the cut off using 730mah is the battery C rating at 13C continuous for 730mah compare to 15C for 2100mah.

Jonathan

Hi Jonathan,

Suppose the same motor is being run on 2 cells and then 3 cells, the current on the 2 cells setup will be higher. Because the esc is trying to provide the same power

Power = current x Voltage

For a battery, when you draw current from a battery, voltage will drop.

Because of the lower capacity of 730mA, your battery voltage drops quickly compare to the 2100mA. The esc trys to compensate by giving a higher current for the same power. This process repeats until your current reach 730mA x 13c = 9.490A
It holds this ways until the batt voltage goes below the esc battery cutoff point and the your esc cut the circuit.

I guess that is the reason for your high current drawn on the 730mA setup. I might be wrong.

[JYZoom]

correct.

collectivepitch,

I think your answer is correct, that is what I observed the voltage drop quite a but when using the 730mah.

Thank you.

Jonathan

Hi Jonathan,

Suppose the same motor is being run on 2 cells and then 3 cells, the current on the 2 cells setup will be higher. Because the esc is trying to provide the same power

Power = current x Voltage

For a battery, when you draw current from a battery, voltage will drop.

Because of the lower capacity of 730mA, your battery voltage drops quickly compare to the 2100mA. The esc trys to compensate by giving a higher current for the same power. This process repeats until your current reach 730mA x 13c = 9.490A
It holds this ways until the batt voltage goes below the esc battery cutoff point and the your esc cut the circuit.

I guess that is the reason for your high current drawn on the 730mA setup. I might be wrong.

[rc1q2w3e4r]

Voltage

That's spot on.

The voltage dropped so much till the low voltage cutoff and cause the shutdown.

Anyway, we had great success with self wound CDRom motors from gobrushless.com

Linearity has never been a problem and much depends on the style and quality of the windings.

The rotating bell and it's magnets make a big difference also.

Cheers !!!