Slow 8520 motor, mosfet or Arduino nano

[afedorov]

Hello.

I am working on a small drone project. I used breadboard to connect motor,mosfet,nano, LIPO battery for testing. Motor spins pretty slow. It cannot lift the frame without any extra load, doesn't even move it.

I am trying to understand what is the reason.

Here is the circuit:

I use:

• arduino nano

• brushed motor 8520 - 4X Racerstar 8520 8.5x20mm 53500RPM Coreless Motor Upgrade for Eachine QX80 DIY Sale - Banggood USA sold out-arrival notice-arrival notice

• MOSFET P30N06LE - https://www.amazon.com/gp/product/B071Z98SRG/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

• LIPO battery -3.7V 750mAh https://www.amazon.com/gp/product/B074J74S2K/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

I pushed motor to the highest value( analogWrite(3,255) and measured the voltage across motor's pins. It was 2.7-3V. It looks too low.

What can be the issue of slow motor? Is it possible to test separately motor, transistor and nano and check if one of them is "broken"?

[Wawa]

afedorov:
I used breadboard to connect motor,mosfet,nano, LIPO battery for testing.

A breadboard can't handle the ~8Amp stall current of each motor.
And maybe your battery/mosfet/motor wiring has problems with that too.
Do you have a schottky diode across each motor.
How is the Nano powered.
Post a real picture of the Nano setup, instead of a useless universal Fritzing picture of an Uno.
Leo..

[afedorov]

I used N4001 diode.

Here is the picture of circuit.

Nano is powered via usb. Grounds are connected.

Only one motor is powered.

[Wawa]

afedorov:
I pushed motor to the highest value( analogWrite(3,255) and measured the voltage across motor's pins. It was 2.7-3V. It looks too low.

Every wire and breadboard contact is a resistor.
Thin wires have a higher resistance.
I guess you have about 50cm of thin wire between the battery and the motor.
That will have some voltdrop when the motor has to work hard.
You could measure where the most voltdrop occurs.
Leo..

[afedorov]

Thank you. I will measure volt drops and reduce length of wires.

Is it safe to do a simple test - just plug in my 3.7v lipo to a motor?

[jremington]

Is it safe to do a simple test - just plug in my 3.7v lipo to a motor?

Yes.

You should solder all motor and power connections. You may have damaged the breadboard tracks with your early experiments, as they can be burned by currents of less than 1 Amp.

[afedorov]

Thank you everyone. The bad connection was the root cause of the problem. I soldered mosfet, motor, power and it works.