Power problem with using arduino mega with motor shield.

We are going to do a maze solver robot. We bought arduino mega and a clone motor shield.

When arduino connected to pc, motor shield easily drive 2 dc motor without any external power supply.

When i disconnect arduino from pc, and connect it to 9v battery, it resets itself continuously. Then i connected another 9v battery to motor shields external power supply pins. And i get an arduino with 9v and a shield with 9v battery. Motors spin but its again not stable arduino resets itself after 1 seconds.

With a little research i learned i can disable shields ext_power pin which is connecting with arduinos Vinn pin. Tryed this but nothing worked :confused:

Thanks !

9v battery

Are those the little rectangular "transistor" batteries? If so they will very likely not supply enough current for a motor. You should find out the stall current of the motor and use a battery that is capable of supplying that current.

Thank you for answer.

Yes, rectangle ones. Is it possible to use 3.7v 2400mah (20a current) 18650 battery as power supply to motor shield by disabling its pwr_out pin which connects to arduinos vin pin ? If not why ?

I have no idea of the motor or motor driver specifications so cannot answer your question. To choose a power supply for a motor you need to know the rated voltage and stall current of the motor.

Motors (2) are standart dc 3v-6v toy motor.

What motor shield are you using (link if possible).

Here: Buy Motor Driver Shield with cheap price