I am using Adruino UNOs powered with 9v batteries wired up to an adapter to plug it into the uno. I have noticed that with my old uno, the green "on" light is more faded than with my new ones. I figured it was because the led was getting old, but recently it had become so dim that it is barely visible. Furthermore, the green led on one of my new unos is now faded(ordered it about 2 weeks ago). I use the boards for about 2-3 hours every day. I don't think I should be concerned about the board powering on, but is there any other convenient way to verify the board is turned on? All my voltage output pins are being used in my circuit so I can't just wire up an led to those. Also, am I doing something that is harming my board?
UPDATE: It seems that the old arduino I have stopped collecting data after 30 minutes of use(which is when I assume the light became very dim), and the newer arduino whose light became dimmer also stopped collecting data at 48 minutes. The others whose lights did not dim functioned properly for the full 2 hours. I am using standard duracell 9V batteries to power the old one and Duracell Procell 9V to power the others.
I am plugging in the batteries now(an hour or so after the conclusion of its use) and the light is not longer dim...
The 5V source is giving me 5V right now(otherwise the SD reader would not work). Maybe the board was receiving less power at some point and data was not collected because the 5V output was weakened? Why did this happen? I made sure the battery was plugged in as tight as it could be throughout my data collection.
tonyu22:
the green "on" light is more faded than with my new ones.
That means the 5V rail is dropping.
tonyu22:
the old arduino I have stopped collecting data after 30 minutes of use(which is when I assume the light became very dim), and the newer arduino whose light became dimmer also stopped collecting data at 48 minutes.
You're using batteries and after a couple of hours your LEDs get dim and the Arduino stops working. There is an exceptionally obvious reason here.
tonyu22:
I am using standard duracell 9V batteries to power the old one and Duracell Procell 9V to power the others
9V batteries have a very (very) small energy capacity.
An Arduino board by itself draws at almost 50mA when powered through Vin. Plus what ever other hardware you have,
But at 50mA, a 9V will only last about 10 hours. If the draw is 100mA (more likely since your circuit has other stuff) the life will be less than 5 hours.
If you're using re-chargeable batteries, those numbers are probably cut in half.
tonyu22:
The 5V source is giving me 5V right now(otherwise the SD reader would not work).
No. That's not a valid assumption at all. The correct method is to MEASURE the voltage at the 5V pin.
tonyu22:
Maybe the board was receiving less power at some point and data was not collected because the 5V output was weakened? Why did this happen?
If the regulator overheats, some of them will rollback the output voltage to lower the current.
So that could also be the issue, depending how much current you're drawing.
And 9v batteries like smoke detectors use are awful, dont use them to power arduino projects
Sd cards run at 3.3v, and probably work a little below that. So your 5v sd card board would have a little on board regulator. If it's got a dropout of 1v, it could still work with significant voltage droop. Measure the voltage with a digital multimeter. Basic ones are quite cheap and a must have device for any sort of electronics work.
