Battery Level Indicator

INTRODUCTION

Battery level indicator  based on lm3914 IC (Integrated chip) indicates the status of the battery by glowing LED’s. For example six LED’s are glowing means battery capacity 60% remains. It can be used to check car battery or inverter. The IC LM3914 takes input analog voltage and drives 10 LED’s linearly according to the increasing/decreasing input analog voltage.

CIRCUIT DIAGRAM

Circuit Components:

  1. LM 3914 IC   
  2. LED’s -10SPST switch
  3. Resistors -18k,4.7k, 56k
  4. Potentiometer – 10k
  5. 12V battery
  6. Connecting wires   

In this circuit LED’s (D1-D10) displays the capacity of the battery in either dot mode or display mode. This mode is selected by the external switch sw1 which is connected to 9th pin of IC. 6th and 7th pins of IC are connected to the ground through a resistor. This resistor controls the brightness of LED’s. Here resistor R3 and POT RV1 forms potential divider circuit. Here pot RV1 is used for calibration. There is no need of any external power supply to this circuit.

The circuit is designed to monitor 10V to 15V DC. The circuit will work even if the battery voltage is 3V. The operating voltage of this IC is 3v to 25v DC. Lm3914 drives led’s, LCDs and vacuum fluorescents. The IC contains adjustable reference and accurate 10-steps divider. This IC can also act as sequencer.

Different color led’s can also be connected to indicate the status. Connect D1 to D3 red LED’s which indicates shut down stage of your battery and use D8-D10 green color LED’s which indicates 80 to 100 percentage of the battery and use yellow color for remaining.

Steps to operate

  • Connect 12V DC battery to the input.
  • Now adjust the pot RV1 so that LED D1 just starts glowing.
  • Now increase the input Dc voltage slowly and observe the LED’s
  • First led will glow for 1.2V and second LED is for 2.4 V and so on.
Battery Level
Percentage
Status of LED’s
1.2V
10 
D1 - ON
2.4V
20
D1, D2 - ON
3.6V
30
D1, D2, D3 - ON
4.8V
40
D1, D2, D3, D4 - ON
6.0V
50
D1, D2, D3, D4, D5 - ON
7.2V
60
D1, D2, D3, D4, D5, D6 - ON
8.4V
70
D1, D2, D3, D4, D5, D6, D7 - ON
9.6V
80
D1, D2, D3, D4, D5, D6, D7, D8 - ON
10.8V
90
D1, D2, D3, D4, D5, D6, D7, D8, D9 - ON
12V
100
ALL LED’s - ON

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