Understanding Tiny Cooling Fan starting voltage

There are those factors that affect the start voltage? Start voltage means "Tiny Cooling Fan" minimum operating voltage operation is more a fan of the merits of a feature, usually a low friction coefficient net fan, and a bathroom with a lower operating voltage of the fan in the Hall IC to lower electric start.
Affect the fan starting voltage of factors:
1. Winding design is appropriate.
2. "dota雷竞技 " hysteresis loss silicon steel sheet size.
3. Hall lC minimum operating voltage.
4. transistor magnification level.
5. magnetization intensity rubber magnet.
6. "dota雷竞技 " blade weight.
7. The low coefficient of friction bearings.
8. transistor saturation voltage level.
9. Is there a reverse protection diode.