What's happening with my cdrom motor?

[rosco]

I've got a brushless motor out of a CDRom and tried hooking it up to a speed controller that I have with a 2 cell 7.4V lipo. It seems to work well until the throttle gets up to about 4/5ths, then it seems to 'cough and splutter', like a missfire...
Is it because the motor can only take about 5 or 6 volts, or is it having trouble spinning the prop any faster?

[LBMiller5]

What wind are you using on the motor, and what prop are you using? I had the same thing happen to one of mine, and when I went to a smaller prop it ran fine. The problem is a result of the timing of the ESC getting out of sync with the motor. If your controller has adjustable timing, you can reduce the advance a little. If the ESC does not have adjustable timing, then the only recourse is to go to a smaller prop, or one with a little less pitch.

Lucien

[rosco]

Yeh, thanks for the reply.
Its a motor straight out of the CDrom, so I cant count the winds and the wire size.
If I put a smaller prop on it , it is fine...so I guess that the magnets in it are not powerful enough or something like that.
cheers
rosco

[rosco]

The prop I was trying is a 7X6...so it was pretty hefty. Its fine with a smaller prop

[olmod]

Many have tried few have succeeded :) they must be remagneted at least,
and if the windings are under .2mm (32g) you will have to rewind those too,
in any case for that size prop its a cert' check out the manual on www.strongrcmotors.com cheers.

[LBMiller5]

If you are using the stock wind, then you are most likely running into stator saturation. Most of the stock winds I have seen have around 50-60 turns of 28 or 30 gauge wire, and are only good for about 10 watts of input power before they start stuttering. I tried one once, and the biggest prop I could put on was a 7 x 3.5. Any bigger and it would start to stutter above 3/4 throttle. I was running a 2 cell Li-Po, and anything over about 2.5 amps would saturate the core and the motor would start acting funky.

To get any real useable power out of a CD-ROM motor, you have to re-wind it at a minimum, and then change the magnets to get it's full potential.

Lucien

[rosco]

Thanks for your input!
rosco