Arduino Uno R4 IoT not working when powered by 9V battery only

[epsilonorionis1]

Hi everybody,

I'm experiencing an issue with my Arduino Uno R4 IoT. When connected to my PC via USB, it works perfectly - I can send signals through Arduino Cloud to turn the built-in LED 13 on and off without any problems. The dashboard works flawlessly and everything communicates as expected.

However, when I try to power the board using only a 9V battery, Arduino Cloud immediately shows that the device is offline. The board appears to power on (power LED illuminates), but it cannot maintain the WiFi connection needed for the cloud dashboard functionality.

I suspect this might be related to insufficient current from the 9V battery, especially when the WiFi module is active.

Has anyone else encountered this problem? I'm trying to determine:

• The minimum current requirements for the R4 IoT board
• Whether standard 9V batteries are simply inadequate for this model
• Recommended alternative power sources for portable projects
• Any power management techniques I should implement in my code

Any suggestions or experiences with powering the Uno R4 IoT from batteries would be greatly appreciated. Thank you!

[kmin]

9V "box" battery is almost never good power supply choice.
But to be sure it's power related problem, try to power your arduino through USB charger.
What is R4 IoT exactly?? R4 Wifi?

[KurtE]

Also check your code does not have something like:
while (!Serial) {}

That waits forever for the serial port

[epsilonorionis1]

Yes, it's an Arduino R4 WiFi

[epsilonorionis1]

No, the code doesn't wait for Serial availability. I've already verified that type of problem.

[kmin]

@epsilonorionis1

Yes, it's an Arduino R4 WiFi

My rough estimate would be ~100mA current draw with peaks at 300mA.
Fresh 9V Duracell should be able to handle that. But 4 or 5 AA batteries would be much better option.

[epsilonorionis1]

Thanks. I will try this solution and let you know