This project details how to build a wide-range Battery Level Indicator circuit capable of monitoring battery voltage from approximately 3v up to 25v. This is commonly achieved using the specialized LM3914 IC, which provides a simple and effective way to convert an analog voltage input into a visual display on a series of LEDs.
Components Required
- IC-LM3914
- LEDs: 10 (Red-3, Yellow-4 and Green -3)
- Resistors: 4.7 Kohms, 18 Kohms, and 56 Kohms
- Variable Resistor: 10 Kohms
- Battery-9v (to test)
- Zero PCB
- Connecting wires
Working Principle:
This project helps you see how much charge is left in a battery by lighting up LEDs like a fuel gauge.
The LM3914 is a special chip that can measure the battery’s voltage and light up to 10 LEDs to show the level. When the battery voltage is low, only a few LEDs glow. When the battery is full, all the LEDs light up.
Here’s how it works: The battery voltage goes into the LM3914 chip. Inside the chip, the voltage is compared to set levels using built-in circuits. The chip then lights up the LEDs based on how high the voltage is. For example, if the battery voltage is half, the middle LEDs will shine.
You can connect the battery voltage (from 3 volts up to 25 volts) through a voltage divider circuit to the chip’s input to make sure the voltage is at the right level for sensing. The chip controls the current for the LEDs, so no extra resistors are needed for each LED.
You can also choose to display the LEDs in two modes: “bar mode,” where all LEDs up to the level are lit, or “dot mode,” where only one LED shows the current level.
This simple indicator lets you quickly and clearly know the battery power, making it handy for all types of battery-powered devices.
This battery level indicator is a practical project used for monitoring power tools, vehicle batteries, and custom electronic projects.
Watch the full video tutorial here: How to make a Battery Level Indicator (3v-25v)