# Car Light. Home Utility Circuit 28 This is a simple 10 Watts LED light you can easily make. It will help you to check the engine, battery terminals or other parts of Car during night. It will act as an efficient high intensity Torch light. It is also useful to check the inverter and its battery usually placed in low light areas. By hooking the clips in the battery, the light will turn on. If you fix a Magnet with it, you can stick the lamp to the vehicle’s body so that your hands will be free to do work. Let us make it. Its cost is Rs.50 only.

Something about 10Watts LED

High Power 10 Watt LEDs are now available that gives the light equal to 60 Watts. It is a large Chip that contains 9 LEDs each rated 1.3 volts. It requires 12 volts and 800 mA – 1 Ampere current. So simple Capacitor power supply cannot give full brightness in this LED. A 12 Volt 1 Ampere SMPS based LED Driver or 12 volt battery is needed to drive the LED in full brightness. It gives 900 lumen and its Colour temperature is around 6000-6500 K. It emits White light with a beam angle of 140 degree.
The chip is mounted on a heat sink, but it requires an additional heat sink to dissipate heat. CautionDo not look directly at the LED because its high intensity light can harm the eyes. Mask with hand or paper while testing. Always avoid direct viewing.

See the calculation to determine the Power output.

P= IV. Here P is the output power in Watts, I is the current in Amperes and V is the voltage.

The LED Chip has an  array of  9 LEDs each has a forward voltage of 1.3 V. There are 9 such LEDs in the common chip making the chip as 12 V ( 1.3 x 9 = 11.7 V ) It is rated as 10 W and the total forward voltage is  11.7V , roughly 12 V. So we know P and V, then I will be
P / V = I – That is 10/12 = 0.833 Amps or 833 Milli Amps. So the LED requires 833 mA current to get maximum brightness. But it is better to add a current limiting resistor with a value 10 – 33 Ohms to reduce the current to half or less. Even though some brightness reduction occurs, it will increase the life of LED. Here I is the forward current of the LED. V is the Forward voltage of individual LED in the array x Number of LEDs in the array. Now the formula comes like this

P = Forward current x LED voltage (1.3V) x Number of LEDs ( 9 nos )
P= 0.833 x 1.3V x 9 = 9.74 Watts.

The LED works well in 9 Volts also, but current should be around 1 Amps. Its cost is around Rs.25
See the photos showing the step wise method to build the light.

Take a piece of Aluminium sheet and drill two small holes at one to  take the wires. The aluminium sheet will act as the handle for the light and also acts as a good Heat Sink for the LED. Take the positive wire through the hole and solder to the Positive terminal of LED. Remember, the exposed part of the wire or the LED terminal should not touch the aluminium sheet. Apply some heat sink compound on the heat sink of the LED to make firm contact with the aluminium sheet. Solder the negative wire also. Fix the LED firmly on the aluminium sheet and apply some glue. Take a current limiting resistor ( 10 to 33 Ohms 1 Watt) . Here 33 Ohms 1 watt resistor is used. So the current will be 363 milli amps, so that each LED in the array gets 40 mA current. Each LED requires 40 – 100 mA current at 12 volt.  Solder the resistor in the Positive wire. Enclose the resistor in a heat resistant sleeve.  Connect two Crocodile clips to hook in the battery Power it, it is working. See it is giving a flood light even in the camera flash Very high intensity light in dark Good light for working in the Inverter set up. It can help to check the battery terminals, water level of the battery etc. Its light is similar to a 40 watts Tube light 