LM3914 12V Battery Monitor Circuit

LM3914 12V Battery Monitor

LM3914 12V Battery Monitor Circuit

This bar graph LED battery level indicator circuit is based on LM3914 monolithic IC from National Semiconductor that senses the voltage levels of the battery and drives the 10 light emitting diodes based on the voltage level that is detected.

LM3914 12V Battery Monitor Circuit

R1 56kΩ
R2 18kΩ
R3 3.9kΩ
VR1 10k Preset
D1 – D10 LED
IC1 LM3914

To calibrate the circuit it must be connected to an adjustable regulated power supply.
Connect an input voltage of 15 volt between the positive and negative poles and adjust the 10K preset until Led 10 lights up. Lower the voltage and in sequence all other Led’s will light up. Check that Led 1 lights up at approximately 10 volts.

This circuit to your own needs by making small modifications. The circuits above is set for ‘DOT’ mode, meaning only one Led at a time will be lit. If you wish to use the ‘BAR’ mode, then connect pin 9 to the positive supply rail, but obviously with increased current consumption.

The LED brightness can be adjusted up- or down by choosing a different value for the 3K9 resistor connected at pin 6 and 7.

You can also change the to monitoring voltage level.

For example, let’s say you wanted to change to 12 – 15 volt,
Remove the R2 resistor and connect 15volt to the input (+ and -) and adjust the 10K potentiometer until Led 10 lights up. Connect  200 Kilo-ohm potentiometer at pin 4 and -. Reconnect a voltage from 12 Volt to the input. Now adjust the 200K potentiometer until Led 1 lights up. When you are satisfied with the adjustment, feel free to exchange the 200K potentiometer with resistors again.(after measuring the resistance from the pot, obviously).

LM3914 12V Battery Monitor test circuit LM3914 12V Battery Indicator LM3914 12V Battery indicator test circuit

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40 comments on “LM3914 12V Battery Monitor Circuit
  1. Ankit says:

    I have used R1=56K ohm,R2=33K ohm & R3=1.2K ohm.
    Whenever I test a battery either 9 V or 3.7 V , then it always glows 9th LED.Why so?

    Please feel free to tell me

    Please if any one knows the answer,tell.

  2. Irfan says:

    Hey – Thanks for the diagram. I’ve made this up and working perfectly for my 12v and 6v battery monitering.

    Its pretty simple and well elaborated by the Author. GOOK WORK!!!

  3. peter says:

    Thanx for the circuit,i needed it for a baitboat i made and i want to check the 12v battery i am using.

  4. khalid says:

    i made this circuit but four Red LED could not light up……….why?

  5. khaled says:

    i made this cercuit. But four Red LED could not light up……..why?

  6. Mustra says:

    Hi, im a newbie at this and i need a monitor for my 4.6V dc battery from my cellullar that now has a different use. is there something special i should do for that circuit to work with my battery?

  7. jim says:

    hi , thanks a lot for this circuit it’s very useful ,
    I just want to know if I can modify it for my 24Vdc
    I have a 24Vdc and 12Vdc cigarette lighter in my CAB truck SCANIA , but I use a ( 0-30Vdc , 10A ) regulator
    for my LAPTOP so I need the 24Vdc plug , that’s why
    I need a 24Vdc discharge battery warner
    thanks nice time

  8. NitroNick says:

    Just want to say thanks for this circuit! I have a Radio Controlled Boat that I use for fishing and wanted a way of monitoring the battery and this little baby was spot on. Brought parts from Maplins for around a tenner.

  9. Thanks for posting, i learn more knowledge on electronics equipment and their uses. As i plan to set up mine but don’t have enough knowledge. At this time i do research more and more to learn everything. Good thing you have posted it. Have a great day! :)

  10. WP Themes says:

    Genial post and this mail helped me alot in my college assignement. Say thank you you as your information.

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