This article is about battery status indicator. Here LED is used to indicate the status of battery either below certain amount of charges or above. I will show you the basic concepts as well as the operation of the circuit. The circuit is very simple and easy to implement.
At first see the circuit below,
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| Fig: Battery Status Indicator Circuit |
Description:
As you can see in the circuit, there are two LED's in this circuit( LED1 & LED2). Here I used green LED to indicate that battery is over charged or fully charged and red LED to indicate the battery as low. The operation is nothing but you need some basic electronics knowledge about transistor. Here I used the BC547 NPN transistor for Q1 & Q2. You can also use BC549 which is also a NPN transistor. When battery goes below a certain amount (according to your demand) of voltages level, the LED2 will turn on. When battery will be charged above that level, the LED2 will turn off. After few times when it will charge fully, the green LED1 will turn on. The user may be noticed by this indication.
As you can see in the circuit, there are two LED's in this circuit( LED1 & LED2). Here I used green LED to indicate that battery is over charged or fully charged and red LED to indicate the battery as low. The operation is nothing but you need some basic electronics knowledge about transistor. Here I used the BC547 NPN transistor for Q1 & Q2. You can also use BC549 which is also a NPN transistor. When battery goes below a certain amount (according to your demand) of voltages level, the LED2 will turn on. When battery will be charged above that level, the LED2 will turn off. After few times when it will charge fully, the green LED1 will turn on. The user may be noticed by this indication.
Parts List:
- Q1=Q2 = BC547 or BC549, NPN transistor;
- R1=R2 =R5=10 k-ohoms;
- R3=R4 =1k-ohoms(variable);
- LED1 = Green color LED;
- LED2 = Red color LED;
- D1 = Zener diode; Choose the value according to your design. For example you wish to operate the LED's between 5 to 7 volts, chose a value of zener diode between these voltage level (6.2V).
- Your Battery;
- Variable DC power supply for calibrarion (0-9V)
Transistor Operation:
You know that transistor is the current controlled component. When you will take a transistor in it's active region from cut off & by step saturation region controlling collector emitter current by base- emitter current, there will create a short path from collector to emitter. Current will follow this direction. and the LED connected to this transistor's collector will turn on. This is the main operating principle of this circuit.
Instructions:
Assume that, you wish to design the circuit for 6v battery. Design the circuit as shown above. For calibration according to your demand, connect a variable power supply (0-9V) at the battery position..Both the knobs of variable resistor should set at zero. Set the voltage about 5 volt or near to 5 volt, adjust the R4 until the LED2 turn on. Make sure that, green LED1 is off. Now increase the voltage up to 6.9 or 7 volts.At this point adjust the R3 , until the LED1 turn on, making sure that LED2 is turn off. Now check your calibration by varying the voltages 0-9V at which point your LED2 turns on/off and at which point LED1 turns on/off. Now replace the variable power supply with your battery.
*Enjoy with your own designed circuit.
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