Smart Charger - Hack

Smart Charger - Hack

I had problems with my LED light; always when I need it I find the battery empty. So, I opened it to look inside and found this old liquid battery. This type of battery needs to be charged every 3-4 days, and I do not want always to connect to the electricity plug, so I change it with two laptop lithium battery.

Lithium battery will last more for me than the already ordinary batteries installed but at the same time I don't want to recharge it frequently to maximize its efficiency.

So, I decided to make an upgrade to the main board to be controlled by Arduino, so when the battery is lower than 45% the batteries will start charging. Then I added a temperature sensor to the battery to avoid over-heating in summer. At this stage if the batteries are over-heated the charging will automatically stops until it cool down. This way the battery will last long time and will enjoy light when needed!

The device now is working perfectly, but I just read an article and discovered a mistake I did which will affect the device on the long run. Who know it? :)

Step 1: What you need!

Arduino Board ebay

6x 10kΩ resistor ebay

2x 2.2kΩ resistor ebay

Thermistor Sensor ebay

Power Adapter 9V ebay

5V 1-Channel Relay - AC250V ebay

Perfboard ebay

Rechargeable batteries

Rechargeable device depending on what you want to hack

Step 2: Build Voltmeter

Then connect your Arduino to Power Adapter

Step 3: Thermistor Sensor

We are using A0 for voltmeter so connect This one to A1

Step 4: Connect Relay

Relay-----Arduino

GND------GND

VCC------5V

IN----------pin2

And of course the other side of your Relay "Depending on what model you are using

Step 5: Coding and Testing

int thermistorPin = A1;
int Relay = 2;

float vPow = 4.7;

float r1 = 50000.0;

float r2 = 4400.0;

void setup() {

Serial.begin(9600);

Serial.print("\x1B");

Serial.print("[2J");

Serial.print("\x1B");

Serial.println("[H");

Serial.println("--------------------");

Serial.println("DC VOLTMETER");

Serial.print("Maximum Voltage: ");

Serial.print((int)(vPow / (r2 / (r1 + r2))));

Serial.println("V");

Serial.println("--------------------");

Serial.println("");

delay(2000);

}

void loop() {

float v = (analogRead(0) * vPow) / 1024.0;

float v2 = v / (r2 / (r1 + r2));

int thermistorReading = analogRead(thermistorPin);

Serial.print("\x1B");

Serial.print("");

if (thermistorReading <= 50) { digitalWrite (2,HIGH);

}

else if (thermistorReading >= 51) { digitalWrite (2,LOW);

}

if (v2 <= 2.0) { digitalWrite (2,HIGH);

}

else if (v2 >= 3.2) { digitalWrite (2,LOW);

}

Serial.println(thermistorReading);

Serial.println(v2);

delay(8000);

}

Upload the code then open Serial Monitor to see what happening inside your Arduino

The device now is working perfectly, but I just read an article and discovered a mistake I did which will affect the device on the long run. Who know it? :)