running LEDs from battery

[MrSlacker]

hey, i never worked with any types of lights or LEDs so i have no idea how they work. my friend wants to put some kind of lights on his bike, just for the fun of it. i suggested him to try LEDs coz they are cheap. so my question is, can i use AA batteries or other type of batteries to power LEDs. if yes, how many LEDs can i put on 1 battery and how do i connect them. thanks

[Frakk]

id recommend to look on google for some basic tutorials. you can run as many leds as you want, but you have to be carful how you hook them up and the voltage of the battery.

different leds draw more current and need more voltage than others. bigger and brighter leds will need stronger batteries but it is all doable. an average led draws around 0.2mA @ 2V, you can hook them up in parallel on a 1.5V battery and you should be fine.

[Guttenaffe]

Please read my post here about LEDs:

http://www.thebestcasescenario.com/forum/showpost.php?p=1448&postcount=20


To add a little more to that:
If you want 10 LEDs off of one battery and they are all the same voltage and require the same current you can use one resistor. Example: You have 3 LEDs they have the bias voltage of 2.4V per LED and 20mA max current draw.

You can use a 9V battery and power these those LEDs using that formula
( 9V - (2.4V * 3) ) / 20mA = 90Ω resistor to give the series 20mA current.

This is the correct formula for LEDs, some webpages and calculation web-apps are incorrect because they do not understand semiconductors.
You see in all Diodes, there is a forward bias voltage and a reverse bias voltage. The forward bias voltage is for use to make the LED light up. The reverse bias voltage is the voltage that will make the diode "break down" when you have that much potential energy (voltage) such as a positive source on the negative side and a negative source on the positive side of the diode. Once this is broken the diode will become useless and destroyed. We do not want to mess with this, as we wont out LEDs to be light up, this is for other things and can be ignored.

The Given voltage for an LED is the forward bias voltage. This is how much potential energy (voltage) is required on the correct polarized side for current to flow though the device.

Ok, we hook up our voltage source and wow, it just blinked on an died. What happoned?

That is due to the other given information about the LED. There is a current for the LED given (normally around 20mA which is .02A) that is the maximum amount of current that can flow though that LED without damaging it. This is also the exact current you must meet to get the proper mcd (brightness) out of your LED. LEDs do not really use power that is "measurable" that is their magic and reason they will last for so long as ‘flashlight bulbs.” The problem is we have to use a resistor to limit the current that will flow into an LED to keep it from dieing. This resistor is the major sore of power dissipation.

The resistor forumula is explained in my other post.


Maybe I should ask som1 to make my post a sticky somewhere or see if I can write an article for posting on here.

[Matthew]

Lol, he wants to put lights on his bike...post pics of that when its done.

[Guttenaffe]

Maybe he wants lights as "ground effects" such as you see on cars? Or does he want to use them as safety devices?

If he wants light as something for just the sake of glowing color I'd recommend EL lighting, they have 3V converters and also 9V converters for EL-wire, EL-tape, and so forth.

[MrSlacker]

my friend is VERYYY into cars. he loves riced out ****. he wants lights just for the glow like neons in cars.

EDIT: if he gets something like this http://www.elwirecheap.com/eltape.html how can he hook it up to a battery? dont forget i dont know any of this electrical stuff so plz dont use big words. :)

EDIT #2: something like this http://www.elwirecheap.com/noname31.html will do the trick, right?

EDIT#3: got the perfect kit http://www.elwirecheap.com/elwibikit.html what you think? also do you know how is battery life of thise things?

[Guttenaffe]

http://store1.yimg.com/I/glowingstuff_1834_862869
From that webpage you posted there are the portable inverters for EL devices.

As to that kit, if that is what he want then it will work fine.

Batterylife, no idea email and ask their sales team.

[ZeD]

I would hit a rice shop and use the little LED air caps that I see people using. They use what I presume to be little watch batrtries and must last a long time. Depending on the size of the threading he can even put them on his aircaps.

[fishies]

Zed's got a good point. Those little valve stem caps are real good. They last a long while, and it's the easiest method to get what you want, without heavy soldering or math.

[Frakk]

dont forget i dont know any of this electrical stuff so plz dont use big words.
these are really not big words, if you dont understand the basics of electronics, and you are not willing to learn then forget it. get some premade led lights as it was posted before if you dont want to mess with it.

[MrSlacker]

these are really not big words, if you dont understand the basics of electronics, and you are not willing to learn then forget it. get some premade led lights as it was posted before if you dont want to mess with it.
sorry, all i tried to say is it would be nice if you could explain all that stuff in a newbie language. also, i just showed that EL wire website to my friend and he really liked it. so thanks a lot for your help.

[fishies]

If this is something you are truly interested in, you need to invest a little time and money into books. highschool electronics textbooks are a great primer. You will learn everything you need to know from it. If you want to go further, there are more advanced books out there, but start with the basics.

If you aren't willing to put the time in to learn the basics, everything else will be beyond your grasp.

[Frakk]

Well said. There are also lot of good tutorials on the net, and Im sorry but i dont have the energy and time to explain the basics to someone whos not willing to research. What I posted I think it was in a pretty newb language and i coulndt go any simpler. After all its really up to you. As much you put into it, as much you get out of it so go do your homework:)

[MrSlacker]

i know i have to learn about it, but all i asked was if there was an easy way to get glow. you told me about EL stuff and after a little research i found out it will do the trick. when i will need to do some more advanced stuff, i will of course research and read all the books and tutorials in order to learn. i liked EL because they have premade battery packs and everything i need to run EL. i know its the lazy way out but thats what i want to do. i am not trying to start a war with anyone and i respect everyone here. i just get why after i got an answer and thanked for a good advice, i need to get a lecture on how i dont do my research and not willing to learn. if i didnt want to learn, i would just ask someone to do it for me........

[Frakk]

im sorry if you took it the wrong way. anyways if you found what you needed im happy for you. and dont forget to post pics of that pimp bike lol

[fishies]

I'm not starting a fight here. It's not a lecture either. You will find shortcuts don't work. Sure, you can hook a bunch of wires together, and get something to work, however, in the case of say LEDs, they require specific current. Too much current and they burn up, possibly casing fire inside your machine, toasting your computer.

If you aren't willing to do the research, don't do any electrical work on your machine. Buy pre-built stuff. No one here waants to read about some kid burning his parent's house down, with everyone inside. They'll be blaming the modding community before you know it, and that's not fair.


I'm not saying your incapable. I'm saying that without proper instruction, you could build yourself a nice firebomb.

[MrSlacker]

here we go with the LEDs again after i said twice i am NOT going to use them! i know they require work and for a bike, its not worth it. sometimes an easy way out is the right way out...... you know what, lets just forget it.

when he gets a new bike, i promise to get some pics. i might do the same thing just for the hell of it.