Writing speed and power consumption

Hi all, I am working on a weather station powered by 4AA battery pack + a solar panel. I want to reduce the power consumption of my setup and thus I am interested to know if the speed setting (full, half, etc.) affects the battery life. I use the sdfat library.

Moreover, I am planning to use a transistor to turn off sensors when arduino is in sleep mode. Is the sd initialization process required each time I turn on the sd module? I suppose yes, but I want to sure!

Thank you in advance.

The SPI speed won't make much difference.

You need to initialize the SD if you remove power. SD.h has a bug that prevents a second begin call so you will need a patch.

Many low power loggers just allow the SD to sleep at about 100 micro-amps. SD.h has a bug that prevents sleep.

The problem is that SD.h is based on a seven year old version of SdFat and has these bugs.

Please start with this link for low power logger ideas.


Also look at other articles by Edward Mallon.

First of all, thank you. I already used the SdFat library downloaded from here: https://github.com/greiman/SdFat/tree/master/SdFat/src/FatLib I hope it is the right version.

I am trying to reduce the power consumption of my project, but I still have some problems. One of them is the rx led, which is always on when the SD has been initialized.

I used the following code (I was inspired by the Gammon's webpage http://gammon.com.au/Arduino/Temperature_Monitor.ino ):

// Data saving
void saveData(){
  sd.begin(chipSelect, SPI_HALF_SPEED);
  dataString = String(pause) + "," + String(timer1) + "," + String(timer2) + "," + String(sR1) 
  + "," + String(sR2) + "," + String(sR3) + "," + String(sR4) + "," + String(sR5) + "," + String(sR6) + "," + String(sR7); // convert to CSV
  myFile.open("data.csv", O_WRITE | O_CREAT | O_AT_END);
  myFile.close(); // close the file
} // end of data saving

The SD card is correctly initialized, but the rx led is always on and it is responsible for a higher power consumption.

So take a sharp tool and damage the LED until it no longer draws current.

I have tried many times to desolder the LED and I always end up smashing it.

"Real hacking!"