Keeping The Adruino Independently Powered

Hello everyone,

So I currently am running 3 DC motors from my Arduino Uno, and I have the program running fine when it is connected to the computer. The power source of the Arduino is a battery holder with 4 AA batteries. Whenever the Arduino is unplugged the program quits running. I know that 4 AA batteries does not supply enough power. What alternative battery should I use/ how many, without ruining the arduino?

Thankyou -Danny

6 AA batteries will work fine.