AUTOMATIC UNIVERSAL LOW VOLTAGE INDICATOR CIRCUIT (3.7V, 8.4V & 12V) | DIY BATTERY PROTECTOR

In this video, we build a precision low voltage indicator circuit that alerts you the exact moment your battery reaches your pre-set voltage threshold. This prevents your batteries from deep discharging and extends their lifespan. This versatile circuit works seamlessly for different voltage levels, including 3.7V/4.2V Lithium-ion cells (set to 3.5V in this video), 8.4V battery packs, and 12V batteries (can be set to 10.5V). The circuit features a 10k multiturn variable resistor for accurate voltage calibration. How It Works (Fully Automatic): You only need to set your desired low-voltage threshold once using the variable resistor. As the battery discharges and drops down to that set limit (e.g., 3.5V), the LED automatically lights up to warn you that it is time to charge the battery. When you plug the battery in for charging and the voltage rises back up above that threshold, the LED automatically turns off. Components Used: 1x TL431 Shunt Regulator IC 1x 10k Multiturn Variable Resistor (Preset) 1x 1k Resistor 1x 330 Ohm Resistor 1x Blue 5mm LED ⚠️ Important Note: You must use a blue 5mm LED for this circuit. Do not use green or red LEDs. The TL431 has a startup trigger of 2V, which causes the circuit to malfunction with green or red LEDs, but it works with absolute perfection using a blue LED. Watch the complete step-by-step tutorial and circuit diagram inside the video! #LowVoltageIndicator #BatteryProtector #DIYElectronics #TL431 #LithiumIonBattery #CircuitDiagram #NextGenCircuits