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Simple voltage increase for battery-powered LED's

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littlefurious

New Member
I have about 40 12v LED's. I know I could just go buy a 12v power supply, but I was wondering if there was a way I could use some of my massive supply of AAA, AA, C, D, and lantern batteries to get 12v's to power them. Hook them up in series maybe? Any advice would be most welcome, thanks!
 

audioguru

Well-Known Member
Most Helpful Member
LEDs are 1.8V to 3.5V. why are yours 12V? Is it because they have 3 or 6 LEDs in series or because they have a current-limiting resistor built-in?

Alkaline battery cells are 1.6V each when new then quickly drop to 1.2V then slowly continue dropping. 8 cells in series make 12.8V when they are new.

LEDs blow up if you don'y use current-limiting resistors in series with them.
 

littlefurious

New Member
The pack they came in says 12v

They came from china in packs of 20. They say "12v" on the package. I tried connecting them to a AA 1.5v battery and not even a faint glow. Guess I'll just have to wire up a series of 8 batteries and see what that does! Thanks alot!
 

audioguru

Well-Known Member
Most Helpful Member
You didn't say what is the colour of the LEDs. A blue or white LED needs about 3.5V and will not have a faint glow with only 1.5V.

What is the rated current of the LEDs?

Maybe they are 12V incandescent light bulbs.
 

littlefurious

New Member
They already have 6 inch red and black wires coming out of them... i assume that means they already have a built-in resistor? And they are blue and white LED's, 12v, not incandescent. What's the best way to power these? I want to either wire them in series to make a christmas ornament, or to make a big-ass flashlight for fun :)
 

Samomighty

New Member
Have a look at the heatshrink first and see/fell if there is a very small resistor under there, and if there is see how close to the led its soldered as if theres enough of the led leg left you can simply unsolder the resistors.

Sam
 

littlefurious

New Member
So what's the best way to power these for a super-bright ornament to outshine my neighbors, or a super-bright flashlight to blind them when their dog pisses me off :)
 

audioguru

Well-Known Member
Most Helpful Member
Why do you think that cheap Chinese LEDs will be super-bright?
They are probably dim old LEDs that are in a narrow beam because the case focusses the beam. It they don't point directly at you then you can barely see them.
 

littlefurious

New Member
Well I guess I'll find out huh? :) In the meantime, can someone PLEASE answer me the battery question? Assuming these are very bright, what's the best way to power them for retina-melting candlepower?
 

audioguru

Well-Known Member
Most Helpful Member
They will soon burn out if the cheap Chinese LEDs are bright.

But then, my son recently bought a little Chinese "flashlight" at The Dollar Store for $1.00. It has one white LED and is powered from three 1.5V button battery cells with no current-limiting resistor. It has Velcro that wraps around your finger and it shines where you point your finger.
It is very bright but I don't expect it or the tiny battery cells to last long.
 

k7elp60

Active Member
I have about 40 12v LED's. I know I could just go buy a 12v power supply, but I was wondering if there was a way I could use some of my massive supply of AAA, AA, C, D, and lantern batteries to get 12v's to power them. Hook them up in series maybe? Any advice would be most welcome, thanks!

Yes you can connect 8 ea of the AAA,AA,C,or D's in series to get 12V. The life of the batteries will depend upon the current drain by the LED's Some lantern batterys are 1.5V,6V or 12V.
If the package of the LED's is marked 12V then they should light up with 12V applied. Hopefully the wires for the LED's are marked + and - and the LED's have to have the right polarity of voltage applied.

As Audioguru mentioned too much voltage can burn out the LED's if the voltage is to high, so preceed with caution.
 

littlefurious

New Member
Yep i tested them and they're PERFECT! I just used a 9v battery to test one. It was very bright, pure white color. I imagine they'd be even a little brighter with 12v instead of 9v. Hopefully they don't burn out too fast but hey, they were cheap as dirt and they're very bright and clear white. Not all things chinese are bad :)

Now, help me figure out how to totally pimp out a razor scooter or a power wheelchair till it's practically street-legal and super-dangerous :D
 

audioguru

Well-Known Member
Most Helpful Member
Duh! Connect the 12V LEDs in parallel with a 12V battery until the battery is dead.
Why did you ask??

We don't play with cheap Chinese LEDs from E-Bay.
 
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