I am deploying a bunch of arduino Unos throughout my place, all with the same program and same setup. They are all powered by a 12V battery, and they all work fine, except for one. I have the debug LED blink every loop, and this one just flashes waaaay faster than the rest. My switches and other components I have hooked up to it don't work. That is until I plug in the USB to the laptop. As soon as I do this, the blinking speed is normal, all my components work etc. As soon as I unplug it, everything goes back to malfunctioning. The battery is full, no shorts or loose wires, I can't think of anything else.
If I am missing something I would appreciate any help. Thank you!
EDIT: I forgot to mention a lot of the previous posts have mentioned a voltage regulator, but I have Xbees hooked up to all of them, and I can talk to it just fine, so it is powered fine.
I am able to use the power off of the 5V output fine without the usb plugged in, but none of the logic is working. Once I plug the USB into the laptop, however, I now have logic control back.
It is possible your Arduino is resetting often because of low power to the MCU or problem with whatever regulator you are using (onboard or off board). Please post a schematic of your device.