Freezer to Refrigerator Conversion

Introduction

Convert a freezer to a refrigerator, and reduce energy consumption 12x so that your refrigerator uses 8 Watts of average power.

Nearly every household on Earth has a verticaldoor fridge that wastes not only food, but also about 1 kWh of energy each day (~365 kWh a year). Some vertical-door fridges waste as much as 3kWh each day. In a country of a few million households, replacing vertical door refrigerators with chestfridges can save enough energy to allow closing down at least one large power station. Alternatively, construction of a new power station to meet the increasing energy demand could be avoided or delayed. http://mtbest.net/chest_fridge.html

Original Work

This work is based on the Mt_Best_Freezer_to_Refrigerator_Conversion. Important point: reduce power usage to 8 watts for refrigerator.

Wiring Diagram

google doc

BOM

• Arduino Gemma $9.95
  • or adafruit Trinket $6.95
  • or sparkfun Pro Micro $19.95 - Install Instructions
• 24-280VAC Relay $9.95
  • or SainSmart Relay Module $3.99 - Requires 5V Board
• Thermister $0.75
• 10k Resistor $0.95
• USB 5V Charger $3.95
• USB Micro Cable $1.95
• Junction Box $7.23
• Extension Cord - Ace Hardware
• 2 Conductor Speaker Wire - Ace Hardware

Arduino Code

//A1 read voltage
//D3 sensor power
//D7 relay (+)


  volatile int sensorvalue = 328; //define the variable
  int triggeron = 328;         //number that will trigger fridge on
  int triggeroff = 304;        //number that will trigger fridge off


// the setup function only runs once every time the chip is reset
void setup() {
  digitalWrite(3, HIGH); //for powering thermister  
  digitalWrite(7, LOW);  //for switching relay
  pinMode(3, OUTPUT);    //begin operating pin
  pinMode(7, OUTPUT);    //begin operating pin
  delay(20000);          // wait for thermister to get a good initial reading
}

// the loop function runs over and over again forever
void loop() {
  sensorvalue = analogRead(A1);   //read sensor
if (sensorvalue > triggeron){     //if sensor reads over triggeron, turn on
  digitalWrite(7, HIGH);       //turn on relay
  delay(8000);                 //wait 8 seconds
}
if (triggeroff > sensorvalue){   //if sensor reads below triggeroff, turn off
  digitalWrite(7, LOW);         //turn off relay
  delay(8000);                  //wait 8 seconds
}
}

 

Other Options

• http://mikeysklar.blogspot.com/p/yatc.html
• https://www.amazon.com/gp/product/B0002EAL58
• https://johnlvs2run.wordpress.com/2009/10/08/chest-fridge-conversion/

Further Reading

• Refrigeration
• Open_Source_Peltier_Refrigerator