# Question about energy usage for my DIY LED aquarium light



## lybrian1 (Aug 10, 2010)

our electric bill is charged per watt (kilowatt) right?
so i want to make a moon light with a single LED strip from ebay. they are cheap and really bright.

i am not really concern about the electric from one single LED but i want to make it as efficient as possible, no point in wasting electric when the LED is not on. anyways, i found an old outlet transformer that says its 12v which is exactly what the LED is rated to be. i cut then end and crimped it with the LED strip and i attaches a small switch to turn on and off the light easily. it works great the only thing is i realized the transformer still gets hot even when the LED is off. does this mean the transformer is still using electric even though the LED is off?
if thats too confusing i can take a photo.

my other question is IF the LED is rated for say 1 watt. and the transformer is rated at 10watt. how much energy is used when the LED is on? is ti 10watt or 1?


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## arc (Mar 11, 2010)

transformer?

Do you mean this ?

Unless unplugged these adapters will use a small amount of energy "phantom power" but I don't know about it still being hot though.

It should only draw about 1w, the 10w is the maximum power it can draw.


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## lybrian1 (Aug 10, 2010)

yes

i mean it does get a bit warm


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## arc (Mar 11, 2010)

It's not a lot of power but if you want to save the phantom lose, you can use a timer.


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## lybrian1 (Aug 10, 2010)

so do i ahve to consider the Watt or the Amps on the transformer?


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## arc (Mar 11, 2010)

> so do i ahve to consider the Watt or the Amps on the transformer?


I'm not sure of the question here. The adapters will give an output of Volts and Amps. The watts rating is just how much the max watts it can draw. The leds should say how much watts it is drawing.

The only thing I would watch out for from ebay leds is how many milliamps(mA) (1Amp=1000milliAmps) it needs. If it only needs 350mA and you use a 900mA adapter then you will be burning through the leds fast.


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## lybrian1 (Aug 10, 2010)

good to know thank you


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