I built a robot recently, it works perfectly being powered by USB, but when i'm using the batteries to power it, the ultrassonic sensor doesn't work correctly. I suspect the batteries aren't enough.
I'm using 6 1,2V 2500mAh cells, and it powers directly the motors, then the arduino, that powers the sensor and the motor driver.
I think this battery pack should be enough, am i doing something wrong?
PS: I tested with 2 battery packs at the same time (one to the motors, the other to the arduino) and it worked, but i don't want to have 12 batteries on my robot.