- 44

- 0

## Main Question or Discussion Point

Hello guys, I am curious about the effects of increasing the number of coils on the armature of a DC electric motor. Say if I switch from a coil from 80 turns to one with 160 turns (made of the same material) would the rotational speed of my motor decrease

I had several ideas but can't make them connect.

1. Since more wires = larger resistance and if voltage stays the same, there would be less current. However, current affects torque and not rotational speed. (since torque = NIAB) Torque and rotational speed, unless I am mistaken, are not exactly related.

2. More coils = increased torque but like I said above, I don't see the connection between torque and rotational speed.

3. I read something that rotational speed is proportional to voltage, and since voltage is constant, the rotational speed of the larger and smaller coil should be the same.. I interpreted this from this thing I found online..

'Torque' is what makes 'outrunner' motors special. Torque on any motor can basically only come from combinations of:

1. strong magnets (eg: 'N' number, size and coverage)

2. efficient flux path (eg: rotor & stator size, materials, design & construction, air gaps)

3. greater diameter (more 'leverage')

4. many magnet poles

5. many turns

6. high current

7. gearing.

These motors are ideally suited to exploit all of these. However, the last two tend to have negative implications so are avoided in most outrunner designs.

Characteristics that increase RPM are the opposite of all the above (except current probably). In addition,

But it doesn't really make sense that everything would spin at the same rate if given the same voltage.

So I am kinda confused and would appreciate any input on this. Thanks.

**for the same voltage**?I had several ideas but can't make them connect.

1. Since more wires = larger resistance and if voltage stays the same, there would be less current. However, current affects torque and not rotational speed. (since torque = NIAB) Torque and rotational speed, unless I am mistaken, are not exactly related.

2. More coils = increased torque but like I said above, I don't see the connection between torque and rotational speed.

3. I read something that rotational speed is proportional to voltage, and since voltage is constant, the rotational speed of the larger and smaller coil should be the same.. I interpreted this from this thing I found online..

'Torque' is what makes 'outrunner' motors special. Torque on any motor can basically only come from combinations of:

1. strong magnets (eg: 'N' number, size and coverage)

2. efficient flux path (eg: rotor & stator size, materials, design & construction, air gaps)

3. greater diameter (more 'leverage')

4. many magnet poles

5. many turns

6. high current

7. gearing.

These motors are ideally suited to exploit all of these. However, the last two tend to have negative implications so are avoided in most outrunner designs.

Characteristics that increase RPM are the opposite of all the above (except current probably). In addition,

**RPM is roughly proportional to voltage so more volts = higher RPM**.But it doesn't really make sense that everything would spin at the same rate if given the same voltage.

So I am kinda confused and would appreciate any input on this. Thanks.