Arduino SD Card won't record on Battery, works well when connected to USB

Projects General Guidance
1

Intro :
Hello everyone! Currently I'm working with Arduino ATMega2560
As you know there are 2 ways to power arduino
1st by connecting it to arduino via USB
2nd with an external power source

currently I'm using the same as this one
http://playground.arduino.cc/Learning/9VBatteryAdapter
yup, I'm also using the 9V

On my arduino there are :
1 SD Shield with an SD Card
5 TCRT5000 infrared sensor
some resistor
I don't know whether this information will help or not

The problem :
when I connect the arduino to computer via USB, the arduino works well. It could record the data from the infrared to the SD Card

But a problem occurs when i connect it to an external power source
Condition :

  1. The arduino is turned on (the red lights and the green lights are on)
  2. it seems normal
  3. When I eject the SD card from the arduino and read it on my computer, There is no data inside it

Assumption :

  1. I don't know if this is a coding problem or not
  2. Maybe a power problem?
2

Since you suspected your code, you should have posted it. If you suspect power, why not getting an AC adapter instead of a 9V battery? You might be both right.

3

Ah I did a simple test with this code that I found (credit to Jerremy blum)
And it turns out that the SD card won't record a simple hello :S

#include <SD.h>
#include <SPI.h>

//SPI Settings
//MOSI, MISo, SCLK Set by default
int CS_pin = 10;
int pow_pin = 8;

void setup()
{ 
  Serial.begin(9600);
  Serial.println("Initializing Card");
  //CS Pin is an output
  pinMode(CS_pin, OUTPUT);
  
  //Card will draw power from Pin 8 so set it high
  pinMode(pow_pin, OUTPUT);
  digitalWrite(pow_pin, HIGH);
  
  //Check if Card is Ready
  if(!SD.begin(CS_pin))
  {
   Serial.println("Card Failed");
   return; 
  }
   Serial.println("Card Ready");
}

void loop()
{
  String dataString = "Hello";
  
  //open a file to write to
  //only one file can be open at a time
  File dataFile = SD.open("log.txt",FILE_WRITE);
  if(dataFile)
  { 
    dataFile.println(dataString);
    dataFile.close();
    Serial.println(dataString);
  }
  else
  {
    Serial.println("Couldn't access file");
  }
    
    
  delay(5000);
}

Same problem,but I already change the battery into a 12v and used an adapter to change it into 9v
It works well when I connect it into USB to computer and monitor it with a serial monitor. Any suggestion?

4

What do you mean by not recording? Did you get failure in opening file, starting sd card, or no error but just no text file with hello?

What is a 12V to 9V adapter? Do you have any pictures of your set up?

5

Hi !
I'm having the same problem as you do. Have you figured out any solution?
Cheers

6

gabrielcbco:
Hi !
I'm having the same problem as you do. Have you figured out any solution?
Cheers

As you should have recognized, the post is a few month old. Why not starting a new post?