Power issues, PLEASE HELP

Hello,
I have a robot with 2 9v DC motors, a mini servo and a single ultrasonic sensor. Connected to the computer, it runs fine, but on a 9v battery, it wont work. Is there a reason???

Sorry, Noob here

Your entire circuit is probably drawing too much current; a 9 volt PPA (square battery) can’t supply enough current, causing a voltage sag and (likely) resetting the Arduino…

Hi,

I don't know what your setup is, but first of I would just like to ask the question of how you power 2 9v motors from usb which only supplies 5v? And if you connected the power jack to the battery yourself, make sure the polarity is alright and you don't cross the current limit of 800 mA at 5V.

cr0sh: Your entire circuit is probably drawing too much current; a 9 volt PPA (square battery) can't supply enough current, causing a voltage sag and (likely) resetting the Arduino...

Do you have any ideas on how to maybe fix that?

My setup is that the negative leads of the motors go right into pins 2 and 4 on the arduino, the negative going to ground. to move them I set the pins to HIGH

Do you have any ideas on how to maybe fix that?

1) find out how much current your motors need. 2) find a power source capable of providing at least that.