how to power 4 tiny dc motors

good evening I'm building a mini drone based on the eachine H8. I'm using 4 of these motors KH8C-005, two l293d, one bluetooth module and an arduino uno. My problem is how to connect a voltage source to power the motors correctly. What I did is basically set up the motors in this manner for the first l293d driver Imgur: The magic of the Internet ,for the second driver instead of connecting pin 8 to another battery I connected pin 8 to vcc from the breadboard. When I turn all the motors only three of them turn on at the same time. I also connected a 9v battery to the arduino with a battery adapter and nothing changed. I couldn't find any datasheet for the motors :confused: however I found the characteristics of the battery used for the eachines sold on websites.

Item Name: Lipo Battery
Capacity: 3.7V 150mah
Length of output line: 30mm
Playing time:6-7min
Charging Time : About 20 min

I was wondering if two 9v batteries are enough to power these motors at max speed? I was also wondering if it would be better to use the lipo battery above to power my drone and how would i do it?should I just connect two wires to the lipo battery and then connect it v+ and v- on my breadboard? any help would be appreciate it.

You need a power supply that can supply the correct voltage for your motors and enough current for 4 motors + 50%.

If the motors are intended to run on 3.7V then running them on 9V is a bad idea. And if by 9V battery you mean the rectangular PP3 things used in smoke detectors then they will not deliver enough current to run any motors. They are useless for this sort of thing.

But if the original ran 4 motors on a 3.7V 150mAh lipo what is stopping you from using the same battery?

Except perhaps that an L293D is a really poor motor driver for low voltages.


The L293D is completely wrong for this. It drops 2.5V from your 3.7V, leaving essentially nothing useful.

If you only need unidirectional control you can try a single MOSFET per motor (with freewheel diode across
motor). For better control (ie 2-quadrant 'active braking'), a half-H-bridge using two MOSFETs is needed per motor.

The complication is that you need logic level MOSFETs that work from 3.7V gate drive, not just
5V drive.

You need MOSFETs to get low on-voltage of the switching device - darlingtons are not good enough, single BJTs
cannot handle the high currents.

first of all thanks to everyone who answered me. I found an H bridge that operates from 2v to 8v. I also found more info about my motors :

1.Operating condition
Rated voltage 3.4V DC
Direction of rotation CW and CCW
Operating voltage range DC2.0--4.5V DC
perating temperature range -10-50°C
Motor position all position

2.Mearsuring condition
Motor position horizontal or vertical
Power supply regulated DC power supply assuring unquestionable measuring
regulated DC power supply assuring unquestionable measuring 10-30°C 30-95%
If the judgment is questionable,Measurent is to be made based on JIS Standard Testing Condition(20+2°C,65+5% )
Direction of rotation viewed from output shaft side

3.Electrical characteristics
Items Specification Standard value
No Load speed 67000rpm±15% 67000 rpm
No Load current 200mA max 180mA
Starting voltage 0.8V max 0.5V DC
Stall current 240mA±5% 240mA
Terminal resistance 0.9Ω ±5% 0.9Ω
Insulation resistance 10MΩ min AT 250V DC between
motor terminal and case

As per suggestion I will use the lipo battery to power my motors. My question is how do I connect the lipo battery to my circuit? I made a small diagram of the idea I have please correct me if I'm wrong. Also should I still connect a 9v battery to power the arduino since I'm also using a bluetooth module(hc-06) and I'm also planning to use a bmp180(1.8v-3.6v) and MPU-6050(3v-5v) thanks again!

The LiPo powers the H-bridge. Your small diagram appears missing.

here is my diagram Imgur: The magic of the Internet so then I would need to power one lipo to one h bridge directly ? so use two lipo batteries in total? thanks again

Why do you think a quadcopter needs an H-bridge.
Quadcopter motors only need to turn in one direction.

The L293D is a terrible choice. It has a high dropout voltage and doesn't work on 3.7volt.
You should use logic level mosfets (with a very low Vgs(th)).

Motor datasheet is probably written by sales noobs.
A 0.9ohm motor resistance results in a 3.7 / 0.9 = ~4Amp stall current (not 240mA).

An Uno with 9volt battery is probably way too heavy to lift with a tiny quadcopter.


Please read the first post in any forum entitled how to use this forum.,148850.0.html

Including how to attach your image to your post.
OP's image.

Tom... :slight_smile: