Emergency Light Circuit

Last Updated on March 16, 2024

Simple power efficient and easy to construct LED Emergency light circuit designed with few easily available components and it is very useful during power outage or instant light needs. LEDs used in this circuit are low current high brightness white LEDs hence it will glow longer time with minimum battery power.

Some emergency light circuit utilizes fluorescent tube but that will consume more power and needs step up voltage from battery power. The following circuit utilize the direct supply from battery and doesn’t need step up voltage stage.

Circuit Diagram

Construction & Working

This circuit automatically turns on the LEDs when there is no AC power supply. A Rechargeable Battery (6V, 4.5Ah) connected in common with DC supply circuit and LED array circuit with the help of SPDT (Single pole double throw) Relay.

Here N/O (Normally Open) terminal of relay is connected with DC supply and N/C (Normally Close) terminal of relay is connected with LED array. The coil terminals of Relay is connected to the DC supply, during the input AC power supply presence common terminal of relay attracted to N/O and hence the Battery gets DC Supply for charging. When the absence of AC input supply Relay coil wont get DC supply and hence the common terminal attached with N/C so the battery supply flows through LED array and LED starts glowing.


  • Use proper polarity of Rechargeable battery in this circuit.
  • This circuit involves in handling of High Voltage AC supply, handle with extreme care.
  • Use White LEDs for better light output.


SPDT (Single pole double throw) Relay may have five pins and two for Electromagnetic coil (You can check by continuity test),  one for common terminal, remaining N/O (Normally open), N/C (Normally Close) terminals. Different types of electromagnetic relay available in market we can choose depends on our needs.

2 thoughts on “Emergency Light Circuit

  1. Kindly tell me the battery type to be used in this project… because battery is being charged continuously , how long would this battery survive?

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