But, our charger works on 12V, hence with the help of a Voltage divider circuit the value of (0-14) Volt is mapped down to (0-5)V using resistor R1 (1k) and R2 (500R), like have previously done in 0-24v 3A Regulated Power Supply Circuit, to display the Voltage on LCD using Arduino Nano. But, how can we do this!!Īrduino Nano is 5V operational Microcontroller, anything more than 5V will kill it. With the help of an Arduino Nano and an LCD (16*2), we can display the voltage and current values of our charger. This circuit alone is sufficient for us to make a simple circuit, but with help of few additional set up we can monitor the current and voltage of our charger on LCD, which is explained below.ĭisplay Voltage and Current on LCD using Arduino: The rating of the transformer is 12V 1 Amps. The LM317 is powered by a diode bridge the Diode Bridge itself is connected to a Transformer through connector P1. Hence, in order to control the current and voltage two potentiometers RV1 and RV2 are used respectively as shown in the schematics above. Based on these formulae the value of pot RV1 is selected as 100R. The formulae to calculate the output current is Iout= 1.2/R1. The Current Limiter Circuit, taken from LM317’s datasheet, is shown in the above figure this is a simple circuit which can be used to limit the current in our circuit based on the resistance value R1. You can also use this LM317 calculator to calculate the value of R2. Using this formulae, the value of resistance 1K (R8) and 10K – pot (RV2) is selected. The formulae to calculate the output voltage is Vout = 1.25 (1+R2/R1). Here the output voltage is decided by the resistor values R1 and R2, in our case the resistor R2 is used as a variable resistor to control the output voltage. I would strongly recommend you to read the datasheet of LM317 and understand it, so that it comes in handy while trying similar projects since LM317 is a most used Variable regulator.Ī simple Voltage Regulator Circuit, taken from LM317’s datasheet, is shown in the figure above. Here, in our circuit the IC U1 is used to control the current and the IC U3 is used to control the voltage. For this purpose we have used two LM317 ICs, one is used to control the voltage and the other is used to limit the current. The main objective of our 12V power supply circuit is to control the voltage and current for the battery so that it can be charged in the best possible way. The complete schematics of this Battery Charger Circuit are shown below: This circuit will provide a Regulated DC Power Supply from the AC mains and will work as AC-DC Adapter I have previously created a Variable Power Supply with High current and voltage output. This Lead Acid Battery charger circuit can also be used to charge your mobile phones, after adjusting the voltage and current according to mobile phone, using the POT. The current can be adjusted based on the present Ah rating of the battery. Keeping this in consideration this, small homemade charger will be able to provide you variable voltage and variable current. Current greater than this may harm the battery resulting in reduced battery life. So for a 7 Ah battery the charging current should be around 0.7 Amps. The charging current of a battery is recommended to be 1/10th of the Ah rating of the battery. Now after complete discharge the battery percentage should be around 10.5, this is the time for us to charge our batteries. The Ah (Ampere hours) of each battery may vary based on the required capacity, a 7 Ah battery for example will be able to provide 1 Amps for a duration of 7 hours (1 Amps *7 hours = 7 Ah). Most of the lead acid batteries in the market are 12V batteries. Let's start by understanding few basic things about a Lead Acid Battery so that we can build our charger more efficiently. This project will save yourself from investing in a battery charger and help you to extend your battery life. Most of our electronics projects are powered by a Lead Acid battery, in this project let us discuss how to recharge this lead acid Battery with a help of a simple circuit that can be easily understood and built from home.
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