12V battery level indicator circuit (LED bargraph)

12V battery level indicator circuit with   LED bar /dot display

LM3914.

The heart of this circuit is the LM3914 from national semiconductors. The LM3914 can sense voltage levels and can drive a display of 10 LEDs in dot mode or bar mode. The bar mode and dot mode can be externally set and more than one ICs can be cascaded together to gat an extended display. The IC can operate from a wide supply voltage (3V to 25V DC). The brightness of the LEDs can be programmed using an external resistor. The LED outputs of LM3914 are TTL and CMOS compatible.

Description.

In the circuit diagram LEDs D1 toD10 displays the level of the battery in either dot or bargraph mode. Resistor R4 connected between pins 6,7 and ground controls the brightness of the LEDs. Resistors R1 and POT R2 forms a voltage divider network and the POT R2 can be used for calibration.

The circuit shown here is designed in order to monitor between 10.5V to 15V DC. The calibration of the circuit can be done as follows. After setting up the circuit connect a 12V DC source to the input. Now adjust the 10K POT to get the LED10 glow (in dot mode) or LEDs up to 10 glow (in bar mode). Now decrease the voltage in steps and at 10.5 volts only LED1 will glow. Switch S1 can be used to select between dot mode and bar graph mode. When S1 is closed, pin9 of the IC gets connected to the positive supply and bar graph mode gets enabled. When switch S1 is open pin9 of the IC gets disconnected to the positive supply and the display goes to the dot mode.

With little modification the circuit can be used to monitor other voltage ranges. For this just remove the resistor R3 and connect the upper level voltage to the input. Now adjust the POT R2 until LED 10 glows (in dot mode). Remove the upper voltage level and connect the lower level to the input. Now connect a high value POT (say 500K) in the place of R3 and adjust it until LED1 alone glows. Now remove the POT, measure the current resistance across it and connect a resistor of the same value in the place of R3. The level monitor is ready.

Circuit diagram of battery level indicator using LM3914.

Battery level indicator circuit using LM3914

Cascading two LM3914.

Two or more LM3914 ICs can be cascaded together to get an extended display. The schematic of two LM3914 ICs cacaded together to get a 20 LED voltage level indicator is shown below.

20 LED voltage level indicator

Cascading two LM3914

Few other battery level related circuits that you may like.

1.Simple battery level indicator : This circuit can be used for monitoring the level of 3V batteries. The circuit is based on MN13811G from Panasonic. MN13811G is a CMOS  voltage detector IC that can be used a variety of voltage monitoring applications. In the circuit LED D1 will flash when ever the battery voltage drops below 2.4 volts.

2.3 LED battery level indicator : A 3 LED battery level indicator that can be used for monitoring the voltage level of 12V automobile battery is shown here. Three states of the battery ie; below 11.5V, between 11.5 and 13.5 and above 13.5 are shown by the glowing of LEDs.

3. Flashing battery monitor : This circuit can be used for monitoring the voltage level of 6 to 12V batteries. The circuit is based on transistors and the voltage level at which the LED starts flashing can be adjusted by using a potentiometer.

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17 Responses to “12V battery level indicator circuit (LED bargraph)”

  • peter clarke says:

    can the lm3914 be adjusted for a voltage range of 13 to 13.4 or is this to narrow? ie all leds on at 13.4 and all off at 13 reducing the number of leds on as the voltage drops. I believe this would be dot mode. Not sure what is meant by bar mode?
    can somebody tell me if lm3914 works for this range before I buy the chip. thanks.

  • Raphael says:

    Hi sir,yes your circuit are helpful. you plz help with a circuit diagram of inductive charging. Charge 12v,7a/h lead acid battery. Your help will highly appreciated.

  • Oladipo mumin says:

    Can lm 3915 be used in d circuit?

  • Thuy Tran says:

    Hi Sir,

    Your circuits are great & really helpful. Could you help me in building a circuit for 24VDC battery?

    Thanks and best regards,

  • Dirk Fourie says:

    Good day,
    I built the 12V battery status LED indicator as mentioned above for my own use and would like to incorporate a buzzer to indicate when the battery has reached a certain voltage. Also, is it possible to add a silence button in case the buzzer goes off? The buzzer can be continuous or intermittent. I am a novice building these projects for fun, so I’m not too familiar with all electrical components.
    Thanks for a cool project!
    Regards
    Dirk

  • N.B.MURUGAN says:

    Hi Sir,
    Your circuits are great & really helpful. Could you help me in building a circuit. The idea is simple 12 Volt battery to be charged using SMPS(used for Computers) as well as power Computer. so this circuit will work as UPS. (This kind of circuit is used in Google servers). Pls check out this link http://news.cnet.com/8301-1001_3-10209580-92.html

    The SMPS will work from AC Main supply to power the Motherboard & will charge the 12 Volt battery, when the power supply fails automatically the 12 volt battery will power the Mother board. (Needed the SMPS will out put in 2 voltages 5 & 12 volt that should not change). This will eliminate the requirement of external UPS & the DC to AC conversion can be avoided.

  • bashir ahmad says:

    Dear Sir, first of all i really appreciate your brilliant support and quick response. please help me how to modify this circuit for 6v 4.5ah SLA battery with minimum voltage 5.7v and maximum 7v.

  • Bashir Ahmad says:

    Dear Sir, first of all i really appreciate your brilliant support and quick response. please help me how to modify this circuit for 6v 4.5ah SLA battery with minimum voltage 5.7v and maximum 7v.

    • jim says:

      could you please email me the schematic of the 6V battery level indicator if you have it with you..PLEASE..it is really urgent..thank you

  • Andreas says:

    And also i have used lm3915.is this a problem ?

  • Andreas says:

    Hi,
    I want to use this at 12v 7.0 amp/hr battery used as a solar charger.
    I have tried to make this but with no success. it is not working
    How do you connect the 10k preset. It has 3 pins.

    • pots have 3 pins middle pin is wiper (control pin)

      so the 2 outer edge pins will go to pin 3 of ic and gnd ##the wiper pin will go to pin 5 of ic

      thats from what i can see in the drawing above

  • RusD says:

    Can this circuit to monitor a Li-Ion battery powerpack?
    Of course, it will be used only on demand to see the battery level not to stay permanently connected…
    Maybe a 5 led simple diagram indicator would be more appropriate.

  • Dan says:

    Hi,

    I’d like to use this circuit to monitor 2 12v batteries wired in series. How would I need to alter the circuit to accommodate this?

    Thanks