I am using two motors ( from old two drill machines - same kind, these are 3.6v motors ), connected to arduino + arduino motor shield seeed studio v2.

When I measured the both motors (indvidually) using a multimeter in series with your motor and an about 3.6V power supply, I found that the both are varying from 1.46A-1.47A, (I supposed it as 1.5A)

I tried to use 18v/1.2a battery that was laying at home (from old machine ) what I have noticed is that motors are running for 3-5 seconds than stop, one of the red lights start blinking in the motor shield, then it stops for 3-5 seconds then it works again and loop.

Notes: - The motors are working when I connect them directly to 4.5 or 6v battery. But when I try to assemle everything , it doesn't work (I am adding this just to say that motors are in good health).

  • I tried 14v battery I noticed the same thing.

  • The drill machine is small one (as big as a human hand). Motors from electric drills are designed as high-speed high-torque motors, but I don't think it's too high in my case to be a huge problem. It's 200 RPM DC motor

  • I spent a week looking for answer before posting this thread, I tried every single solution I came across on the web.

What are things that I should consider here, any thoughts.

What did I miss? And what kind of battery should I use ??

1 Answer 1


I have run into similar weirdness myself, and the solution that worked for me is to have separate batteries for the Arduino and the motors. This is more important if your motors run at a different voltage (e.g. 6v or 12v motors), but is useful in any case. This means that, when the motors draw to much from the batteries, the motors will slow down. If the same battery is used for the motors as for the Arduino, then the voltage drop from the motors will also apply to the Arduino; if the voltage drops in the Arduino, it will turn off (and turn back on when the voltage is restored). This is likely what you are seeing.

  • i've just run to try what you have said. I used 9v battery for arduino and ten (10)*1.2v batteries in serie to make a battery of 12v. WHat I ve noticed is that the motors are taking some time before they move (say 5-10 seconds). I don't use sleep() in my program. What I have made is a one command (to debug the problems) to make the both motors moving at 255. Is there any raison behind that ?? One more thing, the motors are moving slower than they supposed to do ? 12v is good voltage to make them run fast. Commented Mar 8, 2015 at 23:01
  • Check the voltage across the batteries used to power the motors, a high load may cause a voltage drop. Also, in your sketch, try turning the LED on immediately after or before turning on the motors - there may be a delay for some reason you're not expecting. Commented Mar 12, 2015 at 20:20

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