LED 12v Emergency Light Circuit Diagram

Here is a simple LED emergency light circuit that you can implement for home lighting during power failures. We know that LED bulbs consume very less power and hence they have a much longer life. This LED lighting circuit design is intended to light automatically during main power failures. So here we are going to help you with the building of cheap emergency lights. The main part of this led light schematic is a relay, which automatically connects DC voltage to the battery when main power is present and connect LEDs to the battery in the absence of main power supply.Upon request from our readers, we have integrated this with an automatic battery charger circuit. See our updated  emergency with automatic charge controller.

Emergency light circuit board diagram

LED+Emergency+Light+circuit LED 12v Emergency Light Circuit Diagram
Click on the image for enlarged view
Also see: Remote controlled lamp circuit

Components Required

  1. Step down transformer-1 (230V to 12V or 110V to 12V)
  2. Diodes-5 (1N4007)
  3. Capacitor-1 (470µF)
  4. Led-1 (Red)
  5. Resistors-2 (1K)
  6. Relay-1 (12V)
  7. Rechargeable Battery-1 (12V)
  8. Switch LED Array (Group of LEDs, See my prototype )

Working of Emergency light charger circuit

  • The step down transformer and the diode bridge rectifier steps down and convert the high AC (in the range of 110V or 230V) voltage to low (12V) DC voltage.
  • The diode D2 prevents the battery charge from flowing back, it acts as a free wheeling diode too.
  • In the presence of electricity, the relay contact connects the NO (Normally Open) terminal to battery. Thus battery charges during this time.
  • We are using a red LED as the charging indicator which glows when the emergency light battery is charging.
  • When supply failure occurs, relay connects the NC (Normally Closed) terminal to the battery.
  • The LED arrays are connected to NC terminal, thus they glow by using the charge stored in the battery.

Emergency+led+light+demo LED 12v Emergency Light Circuit Diagramemergency+light+battery LED 12v Emergency Light Circuit Diagram
Above shows our prototype (Look  inside the case, it is very simple.We are using two 6V batteries in series to get 12V).

Components Pin out


13 thoughts on “LED 12v Emergency Light Circuit Diagram

  1. how many volts is the 470uf capacitors.what is the specefied wattage of the resistors?is there a limit of resistors to be used?thnx..

    • 1/4 Watt Resistor will do. You can use rated 16V capacitors.

      Regarding about the limits of resistors, as far as their circuit is concerned, those resistors are just used as current limiters for the LED. you can use any value as long as the current that will flow to the LEDs are approx. 20mA.
      1K-ohm is good

    • May I know your point of increasing the secondary rectified voltage?
      As I understand, the rectified voltage will be just used to drive current and charge the load battery (Of course, also to maintain the relay on open state).
      Also, increasing the secondary rectified voltage will just increase the wasted power since the first circuit (from the transformer to the relay) does not really have a function rather than charging the battery and driving the relay. In times where the battery is fully charged, current will just flow and flow without any use.

      Or maybe you have good thoughts in your mind on why you are wanting to increase it to 24Vdc. I will be glad to know. Thank you. :)

  2. What concerns me about the design is that when mains power is ON (or when the load battery is charging), there is no stopping to the charge it will get as long as there is mains power. What I mean is the circuit lacks of over-charge protection for the battery. Am I saying the right thing, or I misunderstood the circuit and the operation? Hoping for your reply. Thanks :)

  3. i have 12v/7.2amp.battery,i want to use pirana led to make emergency light,i build 3leds in series,then how many led work for 8hrs.any circuit pl.reply me.

  4. hi kurt, can i see the full view of your circuit diagram (prototype) , cuz i need it for my project. i hope you understand pls.

  5. Hi,

    I have an emergency light set that has all the batteries leaked/dead, I want to modify/rewire the circuit so I can use it as a lamp, always connected to the mains. It is possible?


  6. Hello,

    I came across this page, where can i get the 12v rechargable battery and what would be the approx cost of it?

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