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How can I power 16 LED's with 2 AA batteries? What type of LED's do I need for this? Answered

I found a website that boasts a safety vest with 16 LED's powered by 2 AA batteries (see link at bottom). This confused me because I have a setup of 16 LED's in "series", but my setup requires 18v to operate. Is it the rating of my LED's? What "size" LED's do I need to get to minimize the voltage requirements?

If you're curious, I set the LED's up for my daughters Power Wheels for headlights and tail lights.

http://www.drivingcomfort.com/index.cfm/fa/p/pid/4235/sc/32193

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frollardBest Answer (author)2009-08-28

I second the notion to use the power wheels battery. I would recommend an led driver circuit so they are always bright no matter how high or low the power wheels battery is.

LEDs in series add voltage (16 leds need 32v, only 20ma)
LEDS in parallel add current (16 leds need 2v, but 16x20ma = 320ma)

ideally, run off the (I think 12 volt) battery, 6 leds in series with a small resistor (less than 100 ohms). Run multiple strings for more lights.

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dilandou (author)2009-08-27

To make it a little simpler, try an LED wizard such as this one. You give it the numbers, it'll give you schematics and a wiring diagram, or multiple variations for your choosing.

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kate_delaney (author)dilandou2018-02-18

Great link - thank you so much!!

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kevinhannan (author)dilandou2009-08-28

that's a fantastic link, thanks! ;-)

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The Lightning Stalker (author)2009-08-28

Why not just power them from the Power Wheels' battery? Otherwise, I've got a couple circuits on my site that might work.

http://kickme.to/lightningstalker

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seandogue (author)2009-08-27

6 of one, a half dozen of the other.

to achieve the result, you can
A) use a high voltage source and power the LEDS in series
B) use a low voltage source and power the LED (in series) using a step up regulator
C) use a high voltage source and power the LEDs in parallel using a step down regulator
D) use a low voltage source and power the LEDs in parallel.

Or combinations thereof.

Red leds in general have Vf = ~2V

you'll have to be the judge on the other aspects. I'm just playing the role of Landru, the infoputer.

gotta run eating my peanut butter and jelly dinner.

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