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Steve G.
Steve G., Electrical Engineer
Category: Electrical
Satisfied Customers: 17895
Experience:  Spent 20 years as an Electrical Engineer, designing electrical plans and specifications.
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I need to run a photo cell and LED light and the LED light

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I need to run a photo cell and LED light and the LED light needs to last for 1500 hours. what is the smallest size battery and how many would I need to use?
Hello there and welcome to Just Answer. My name is XXXXX XXXXX I will be assisting you today. I am an engineer with over 30 years of electrical and electronic training, repair and installation experience. I will try and answer your question accurately and precisely so that we can get you on your way.

Now..have you picked out the LED light yet? If not, what kind of light are you looking for? Outside? Flood? Any idea of the wattage?

Please let me know so that we can continue.

Regards
Steve
Customer: replied 3 years ago.

I believe it is a 4.5V. It is just the little diode type of LED light. it is for indoor use.


 

Ok. So a typical LED in that type of application uses about 0.5 watts, which means at 4.5V, it is pulling about 0.11 amps.

To run it for 1500 hours, you will need a battery capable of 1500 x 0.11 = 165AH (Amp Hours).

That is about three car batteries, which are big. Car batts are also 12V so you would need some way of stepping down the voltage.

Have you thought about that?

I'll be here if you need further help with this issue. Please let me know.

Regards
Steve

Customer: replied 3 years ago.


How do I step down the voltage?

You would need a power supply or other solid state electronic device OR you would need 4.5V batteries OR run three of those LEDs in series which would sum to 13.5V which your 12V batteries would like.

I'll be here if you need further help with this issue. Please let me know.

Regards
Steve
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