LED Experiment Question

[Denholm]

Hello everyone,

I've recently gained quite the interest for LEDs and am trying to do some relatively simple experiments. The first experiment will be quite simple, an LED, some wire, a battery case, and some soldering to connect all the pieces. Basically an experiment to power an LED via battery. However, I lack the knowledge on what to buy. Obviously any LED will do just fine, but I'm especially picky about the power source. Yes, I want it to be portable (thus the reason for my calling it a battery case). But I need to know what will work to power a small LED with a relatively low power consumption. I don't want to hook it up to a power source which will cause problems.

So, are there any ideas as to what I should buy which will power my LED via battery?

[Strip]

Need to know the voltage required...

Proposed run time and mA would be a good addition too.

[Denholm]

I believe the voltage required is between 3 and 3.4. Since I'm not familiar with the voltage table for this LED, here's the link:

http://www.lck-led.com/p479/3mm-Round-Led,-30%C2%A2X-Degree,-Normal-Bright---10PCS/product_info.html

The mA is 20. Running time would be a maximum of two hours.

[Fulmar]

Nevermind....will edit later.

{EDIT}

Depending on how small you want this pack, you can use a variety of batteries.  At a 20mA draw, according to Rayovac's specs, you should get approximately 50 hours of run time off a AAA if the battery is drained down to 0.9V per cell (basically the light would be pretty dim at this point).  Since LEDs run ~ 3V, the best way to do this is to hooked 2 AAA in series.  A brand new alkaline AA/AAA/C/D reads about 1.585 to 1.6 volts.

I would avoid using rechargeables since they operated a 1.2V (1.35 to 1.4V when fully charged, but this quickly drops to around 1.2V, and to 1.0 when dead).  One of the reasons why rechargeables are bad in flashlights unless the flashlight is designed to use them.

The other common options would be to use a lithium coin cell.  VERY common in key chain lights.  Most use 1 x CR2032.  Rated at about 240mah or so depending on the brand.  Should give you about 8-10 hours of run time.  

[KgB]

All i know about diod is that it allows an electric current in one direction:)

[Fulmar]

You'll only need diodes if your battery voltage is greater than the rated voltage of the LED.  That is, let say you used a 6V battery, you'd need a diode to lower that voltage down to stop the LED from burning up.  Otherwise, the with the right battery voltage, the LED is only going to draw as much power as it needs.

[FireDrgn]

Just go to the store and buy an LED FLASHLIGHT   Take it apart and solider it together with wires.

When you buy flashlight... YOu get.

LED Light
Batteries
Battery Case

YOu will need to pick up some wire.
The nice thing is you can choose differant wattage and run times before you buy ,and it comes with all the right parts.



<S>
 What is your power source criteria?  You need to pick your battery first then match the LED to fit your criteria.

If your power source criteria matches any common flash light.... just choose flashlight based on battery..

If not post the battery criteria you have and we can pick the right LED to help you meet your goals.

We will need to know voltage, and mA.

[MrRiplEy[H]]

You should also put a resistor in line with the led or the led will burn up. There's a formula for calculating the correct value of resistance.

I have GU10 halogen lighting in my downstairs, 36 x 50w halogens. I've started replacing them with 3W GU10 LED spots. They give roughly 35W worth of light. Buggers cost 20 bucks a piece though.

http://www.pur-led.de/index.php?language=en&cat=c132_LED-Spots--GU10-.html&gclid=CP6E_auK_ZwCFVITzAodWjtNbg

[Seafit]

Not sure of your application but this thread in the Free-track forums was one about simple LED & Battery setups. There are other threads on the same forum, this was just the most recent I had looked at.

http://forum.free-track.net/index.php?showtopic=1856&page=2

[Jenks]

Denholm,
I don't know where you live,  but if its in the U.S., then Radio Shack used to sell some nice experimenters books. These had circuit diagrams, Radio Shack part numbers, required tools , theory of operation, etc.

For experimenting, a "breadboard" is best. Its a grid of circuit connections with holes in it to place components. (no soldering required) A better one will come with binding posts for I/O and power source connection.

LED technology has come a long way and you can now get a number of special purpose led's. i.e. 12v LEDs that already have built in current limit resistors, LEDs that flash, Hi wattages LEDs (all the rave now), just about any color or size.

Regards,

Jenks

[Megalodon]

I'm especially picky about the power source. 
So, are there any ideas as to what I should buy which will power my LED via battery?

http://www.surefire.com/Batteries

[ZetaNine]

Radio Shack is your friend........it's the one thing they still do better than most

rows and rows of kits....converters...and LEDs....for just about any project.

Hello everyone,

I've recently gained quite the interest for LEDs and am trying to do some relatively simple experiments. The first experiment will be quite simple, an LED, some wire, a battery case, and some soldering to connect all the pieces. Basically an experiment to power an LED via battery. However, I lack the knowledge on what to buy. Obviously any LED will do just fine, but I'm especially picky about the power source. Yes, I want it to be portable (thus the reason for my calling it a battery case). But I need to know what will work to power a small LED with a relatively low power consumption. I don't want to hook it up to a power source which will cause problems.

So, are there any ideas as to what I should buy which will power my LED via battery?

[Fulmar]

http://www.surefire.com/Batteries

A bit over kill and not really designed for this application.  The Li-Ion batteries in Streamlight and Surefire flashlights, along with laptops, cellphones etc really excell in high drain applications.  A 20mA LED is FAR from high drain.

Thionyl Chloride Lithium Batteries - commonly found in your Energizer AA/AAA and some other sizes also excell in high drain applications.  In a digital camera, you can get 6-7 times more photos on a Lithium AA as compared to an Alkaline AA because the respond better when the amerage draw is great.  Put your Lithium AA in your TV remote, your performance gains are nullified, maybe 2x longer.

Manganese Dioxide Lithium Batteries - found in your button cell CR2032 or cylindrical 123's CR2's etc, also do well in high drain applications and the same rule applies as above.  However I recommended the CR2032 for their relatively low cost, small size, and the fact they're often used in the application Denholm is using.

CR button cells come in a variety of sizes.  Some of the smaller ones being CR1025, 1216, 1220 and largest ones being in the 3032 range.  The battery number is also its dimension.  A CR 2032 is 20mm in diameter and 3.2mm thick, while a 1025 is 10mm in diameter and 25mm thick.

I'd probably shop ebay or online to get these cheap.  Your local retailers will charge $3-4 on average for a CR2032.  Ebay, I found them a 10 pack for $2.50 w/ free shipping.  At this price, its really close to the cost of what these cells actually cost in bulk.

[Denholm]

Thank you to all who pitched in!

The reason I'm not interested in disassembling a flashlight to obtain the parts necessary for this project is because I'm attempting to learn the basics of assembling electrical components. I would rater match, buy, then assemble the parts myself then buy a kit giving me the whole package.

Fulmar, based on your suggestion I think I'll experiment with the AAA's. Thanks to a high rate of recommendation, I will also peer into a local radio shack to see what they offer in the sense of LEDs, resistors, and battery-operated power supplies.

[FireDrgn]

I kinda see what your saying.....  Your going to end up with those parts anyways are you not.


<S>

Radio shack is the best place to go then....