External supply (9V battery) not working when WiFi shield is attached

Hello,

First of all I'm not sure if this subforum is the most suitable for my question, so please feel free to move it wherever the admins believe is more appropriate.

The problem that I am facing is when I am trying to supply my Arduino Uno R3 and the WiFi shield with a 9V battery.
What happens is that the LED 13 blinks like crazy (all the WiFi shield leds are off).

I tried to reset the board, nothing changed.
I removed the WiFi shield and then the Arduino was working properly.
When it's connected to my laptop it works correctly.
I checked the output of the battery and its 5V (1023 when I placed the battery in one of the analog pins of the board and printed the value).

I uploaded a video here, so you can see the issue*: http://sdrv.ms/1cSGlGO

*I have also tried to remove the cables that you see on the breadboard in the video

Thank you,
panos

I checked the output of the battery and its 5V (1023 when I placed the battery in one of the analog pins of the board and printed the value).

So you put a 9V battery into an arduino? That is going to damage it. Any voltage over the voltage reference will give 1023.
Measure the voltage of the battery with a meter, which I hope you connect through the Vin or the power jack, while the shield is connected. You will probably find it is sagging.

I see .
I suppose I'm lucky, because the board is working.
I don't have a device to measure the voltage, I will try a new battery to see if it's working.

Thanks for your reply :slight_smile:
panos

You really ought to buy a multi-meter.....

JimboZA:
You really ought to buy a multi-meter.....

Will do :slight_smile:

A brand new alkaline battery did the job :smiley:

Thanks guys!
panos

Hi,
A 9v battery are we talking PP3? That will last about 5 minutes!! it does not have the capacity or current to drive a Uno for long, especially one with LEDs and other things hanging on it..
And what was that video supposed to show us? Your hands in the way most of the time, along with a flashy burn my eyes out led!!

You've been lucky, but I've made silly mistakes too, and it's supprising what some IC's will take including putting them in the socket the wrong way, connecting power to the wrong pins, etc.

Hope it helps.
Regards
Mel.