![]() Reference Voltage= 5 volts // internal 5v reference selected ![]() Voltage= (ADC value / resistor factor) * reference VoltageĪDC value= output of Voltage divider (converted into digital by microcontroller) To calculate car battery voltage from the ADC value we have used given formula: To configure ADC here we have selected analog pin AN0 with an internal reference voltage of 5v and f/32 clock for ADC conversion. As shown in below figure, we have cut the red circled connection, it may differ in your car charger. First open the 5v connection from the USB port in the car USB charger and then connect 12v to the USB port where 5v was connected. You need to open the car USB charger and then find the 5v (output) and 12v (input) terminals and then remove 5v connection by rubbing it with sand paper or with some hard thing and short the USB output terminal to 12v directly. We have added a USB port in the PCB, so we can directly connect car USB charger to the circuit.Ĭar USB charger or Cigarette lighter provides 5v regulated supply from the 12v power outlet of the car, but we need to measure the actual voltage of Car battery so we have tweaked the Car charger. Circuit is powered by the USB car charger itself by using a LM7805. A 20 MHz crystal oscillator is used to clock the microcontroller. A 5v voltage regulator namely LM7805 is used to powering the whole circuit including Seven Segment Displays. A zener diode of 5.1v is also used for protection.Ĥ in 1 seven segment display is used for displaying the instantaneous value of car battery voltage that is connected at PORTB and PORTC of the microcontroller. In this Battery Voltage Monitoring Circuit, we have read car battery voltage by using an inbuilt analog pin of PIC microcontroller and here we have selected pin AN0 (28) pin of microcontroller through a voltage divider circuit. Also check the Simple Battery Monitor Circuit and 12v Battery Charger Circuit. Check the Video at the end, where were we have demonstrated it by measuring the voltage of a Variable power Supply, a USB power bank and a 12v AC-DC adapter. For this purpose we have soldered the Terminal Block (green color plastic block) in PCB where you can connect two wires from power source and can monitor the voltage. We can also use the same circuit for measuring the voltage of other power sources up to 15v. But when the battery is not charging or car’s engine is not ON, then the voltage across battery terminal is actual battery voltage around 12v. When a car battery is charging, then the voltage across the battery terminals is actually coming from the alternator/rectifier, that’s why system reads 13.7 volts. This circuit can measure the voltage up to 15v. Then a 4 digit seven segment display is used to show the voltage value of battery. Car Cigarette Lighter or Car USB charger is used for getting the battery voltage to the ADC pin of the microcontroller with the help of Voltage Divider Circuit. In this project, we are going to implement a Voltage Meter for Car Battery by using a PIC microcontroller. So we can identify whether our battery is charging well or not and can investigate the causes of battery failure. The voltage of a 12v car battery during charging is about 13.7v. By this, we can protect battery failure due to the faulty charging system. Generally it is not important to measure the car battery power every time, but we often need to know about battery voltage during charging, to check whether its charging or not. ![]() USB cable (B-type or Arduino UNO compatible) -1. ![]() Common anode seven segment display(4 in 1) -1.We have attached a terminal block here to measure the voltage of other power sources, just by connecting two wires in it from the power source. The PCB also has the option to use it as Voltage Measurement tool or Voltmeter without using USB car charger. This Car Battery Monitoring Circuit is used to monitor the power of Car Battery by just plugging it into the power outlet on the dashboard of a car. ![]() Here we have designed a PCB using EASYEDA online PCB simulator and designer. In this project we are going to make a PIC based Car Battery Monitoring system on PCB. ![]()
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