Fast flashing LED when on battery power...

So I know that it is something stupid I did but I am at a total loss.

I have an Uno and when it is plugged into the USB, the program runs flawlessly. When I unplug it and use battery power, the LED I am using begins to flash very quickly.

The program I designed runs a Morse code sequence once an IR sensor is activated. Like I said, it works fine when using USB to power it but when it is on battery power, the LED begins flashing without initialization.

Could this mean that the LED is trying to draw too much current? Would an LED driver fix this issue?

Any help would be GREATLY appreciated!

Thank you in advance!


Hi Chris

What type and voltage battery are you using? How have you connected it to the Arduino?

Do you have a multimeter to measure the output voltage of the battery?



Post your sketch (use code tags!) and a schematic diagram (hand-drawn is OK), or a well-focussed close-up picture of the circuit. Also links to any important components like the IR sensor.

As long as your LED is just an ordinary 5mm type and you have a series resistor, it won't be drawing too much current.


want pin(s) are you using for battery power ?