i want to add some led's into my passenger pegs since my fender eliminator is cheap and dim as crap...specifically the brake light. i would like to do 5 or 6 led's on each peg...3 reds for the running/brake light and then 2-3 ambers for the turn signals. i read throughout the 7 page DIY thread on here but havnt been able to find a clear answer so i figured itd be best to try here. im pretty sure i know how to do the turn signal part....just wire up the leds together than splice into the turn signal wires in the undertail. the DIY thread explains that part well. the brake light/running light is where i could use some insight as to where i should splice in. the led's will be pre-wired with resistors and from what i read you can twist the + and - of the 3 led's together to make it one big P and one big N instead of 6. i also noticed most only used 6 or 8 total..would 12 led's cause any type of voltage problem?

honestly i havnt looked at the wiring for the brake/running because it was installed before i got it and my trunk latch doesnt work..hoping someone has done this and can give me a good idea as to what i need.....like i said, the diy thread is a great help with the signal wiring but doesnt bring up the brake light.
http://img150.imageshack.us/img150/5331/ups015hj0.jpg

well if you understand how to do the signals, the brake and running lights should be pretty easy for you too. in order to wire 12 leds up, you have to have a few series of 3 or 4 leds wired together.

when you connect each led to each other, with one positive going to the next negative, its called running in series. when you have all the positives connected and all of the negatives connected, its called running in parallel. you need a combination of both in this case. the maximum number of leds you can have in a series is determined by your source voltage (battery) and how much each led drops volt wise. so say your leds use 3 volts to run (called the voltage drop), well you take the 12v from your battery, subtract 3v, and now you have 9v left you can still use. that would be a total of 4 leds, each using 3v for a total of 12 volts. now if you make 3 of those 'strings" of leds, you can wire up all the positives on the strings to each other, as well as the negatives to each other, and now have 12 leds. when making them, you will need 1 correctly calculated resistor for EACH series, so you would need 3 total in this case, 1 in each "string". does all of that make sense?

ok now, so to make it work off of the tail light or brake light, there should be 2 sets of 3 wires at the rear of your bike. a light bulb would usually go to each one of those sets, but it sounds like you have an led taillight. so, in each of those three wires are a ground (negative), a running light 12v (constant 12v), and a brake light 12v (switched 12v). simply wire the negative on your leds to the ground, and then whichever 12v you want, whether running or brake, to the positive side of your leds.

PM me if you need more help!

axsys thank you!! i really appreciate explaining that for me. so if i have the concept correct,if i find 3v led's i would need 3 strings of 4 led's to keep it at 12v. would this little diagram be considered a series? if this is correct the only part im still not positive on is how to connect the 3 strings to one another once this stage is completed
http://img355.imageshack.us/img355/8734/ups015eb2.jpg
theres a bunch of pre-wired leds w/ resistors on ebay for a good price but they say "12vdc"...could i make 12 of them somehow work or is it better to just find ones like 3v as you said


shoot me a reply when you got the time, i really appreciate the help

That is how you would wire in series, however...

Ideally it's better to use individual resistors or pre-wired LEDs, just for the sake that the voltage will change on any automotive application. Even though you have it wired in series to support 12v, your alternator could be putting out closer to 14, which can (and most likely will) cause the LEDs to burn out a lot sooner than later.

You can still wire in series, but you're best to wire for 14v+ in order to compensate. In doing so, your LEDs won't achieve their full brightness potential. Wiring in series is usually ideal for applications in which there is a set voltage that doesn't fluctuate.

Check www.oznium.com for LED products, and their forums for some helpful people. I personally just got done adding 5 3mm pre-wired LEDs to my passenger pegs to use as running lights / turn signals. Looks awesome!

hey aken thanks for the reply

i was actually planning on using the pre-wired led's from oznium but saw the "ships within 5 weeks" part...did your's take that long?

the 3mm yellows are in stock but the reds say 5 weeks. wanna go 6 of each

aken: if i was to go with the ozniums like you, since they are pre-wired with individual resisters how would you recomend wiring them?

whenever you wire leds to anything, it is always recommended to use a resistor, even if its only a few ohms. its not the voltage that you have to worry about, its the amps, which is what resistors mainly limit.

the difference between using leds in parallel (of each one with a resistor by itself) and in series is how much power it takes up. most leds run at around 30mA. when you have a series of leds, the milla-amps running through each component are always the same. so when you have your series of 4 leds, its a total of 30mA running through the entire circuit.

so, each circuit you run is 30mA. with 3 series circuits (4 leds in each series) you run a total of 90mA. but with 12 leds wired in parallel, you run a total of 360mA. now, 360mA is not very much at all, but it does technically take more power to run a parallel circuit.

with pre-wired leds that are setup already for 12v, you just wire them directly to your power source (so black wire to ground, red wire to running 12v or brake 12v, depending on which you want)

to wire up the 3 string to eachother, you would cut your diagram at the bottom where the long red and black wires connect. then, since you have 3 of these strings, you would connect all the long red wires to each other, and then all the long black wires to each other. then, you connect the 3 long red wires to your 12v source, and the 3 long black wires to your ground. does that make sense?

Mine did not take that long, no. Means that the 3mm red are out of stock currently.

As axsys mentioned, you would wire positives to positive sources and negatives to negative sources. No daisy chains or anything.

axsys: Resistors are designed to drop the voltage in relation to the current. They are not designed to change current only. That's a fuse's job. Also when you're dealing with individual LEDs, the current is so small that it is hardly a concern. Using a higher voltage is what you want to prevent. You've got the right idea, though.

Aken, i agree with you. the reason i just mentioned current really is because your source voltage and led voltage drop are constant usually, while your resistor is what you can change around with different ohm values, and running too many mA with the wrong resistor will kill your leds. also, i think you meant that a fuse is designed to prevent the current from getting to high, not changing current, right?;)

Yes, yes I did. Gotta stop posting at 2 am. :)

ok so far this is what i got for one peg...i will be using the oznium 3mm's(pre wired w/ indiv. resistors)
good? no good?
http://img80.imageshack.us/img80/1386/ups015iz0.jpg

Yup yup.

thanks man, you and axsys are a huge help...ill be sure to post up some pics once the led's come and i get to work

no problem. well be waiting for pictures!

J&P Cycle(www.jpcycles.com (http://www.jpcycles.com)) sells a wiring harness/plug that allows you to use and LED(or LEDs) as running and brake/turn signal lights. if anyone wanted to know. i ran into it on accident. lol.

ORIGINAL: ny450

ok so far this is what i got for one peg...i will be using the oznium 3mm's(pre wired w/ indiv. resistors)
good? no good?
http://img80.imageshack.us/img80/1386/ups015iz0.jpg



So am I looking at this correct? Are you running just 1 LED with a resistor to the battery? If so, that is a pretty big waste in my opinion. This is especially true if you are using an LED with a drop of about 3V and lets say 20mA. Assuming a 14V system (as per reasons mentioned above already) that means each resistor is 550 Ohm and the power dissipated by each resistor is going to be 220mW. If you really want me to go through all the math, I will. A lot of resistors out there are only 250mW resistors, and this is going to mean the resistor is going to get pretty hot which leads to premature failure.

The best way to do this would be to use a series of 3LED's then a resistor at the end of the series. This helps minimize parts count, keep the power dissipated by the resistor down, and still provide a good balance of brightness. You can then add as many extra sets of 3 LED's in series plus a resistor as you need/want.

If you want bright LED's, like the kind used OEM in car taillights and such, check out "superflux" LED's. They run at 70mA. I have them stock in my G35, and I have also used them in a turn signal project for my G35. To see which LED's I'm talking about, google LTL911SEKSA, LTL911SYKSA. They are made by lite-on. You can buy them from digikey. Lumileds (made by philips) also make superflux LED's, but I do not know their model numbers off the top of my head.

Superflux LEDs are way too big for the passenger peg application.

ORIGINAL: Aken

Superflux LEDs are way too big for the passenger peg application.


That could be. I never actually tried fitting one on there. They are generally 7.62mm x 7.62mm cases. To me it just seems like 3mm LED's won't be really bright enough to do much, especially in the daytime. Just my opinion though.

Mine look great in the daytime. I left them at full brightness, didn't dim them down for running lights, though.