LED tail light conversion
Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=36575
Printed Date: April 23, 2024 at 11:51 PM
Topic: LED tail light conversion
Posted By: lilboi
Subject: LED tail light conversion
Date Posted: August 01, 2004 at 7:57 PM
I want to do a LED tail light conversion. How would i do this? I have about 200 orange led's laying around. I don't plan to ues all of them. How would i wire this to a board?
Replies:
Posted By: archemedes
Date Posted: August 01, 2004 at 9:16 PM
I made some with red ones, and just wired them onto a piece of circuit board, and then added a resistor to get the right voltage to teh lights, if you use enough led's though you don't need the resistor. I'll see if I can find my instructions
Posted By: xetmes
Date Posted: August 01, 2004 at 9:19 PM
what is the forward voltage? the current you want through them? I have done these for smaller lights, very time consuming but looks good if you take your time. first figure out how many you want in each series branch (by the voltage and current ratings) then just decide how many series branches to parallel together (as many as you want), I usually just use predrilled perfboard (with the copper donuts), break out the soldering iron and go nuts...
Posted By: archemedes
Date Posted: August 01, 2004 at 9:27 PM
here's the site I used to build mine, and they worked great
https://www.myra-simon.com/bike/LEDlight.html
Posted By: Velocity Motors
Date Posted: August 02, 2004 at 7:51 AM
Why not buy some LED bulbs, they are cheap ( about $ 3.50 per bulb ) and they have them in 1156, 1157 and 3156
-------------
Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA
Posted By: archemedes
Date Posted: August 02, 2004 at 3:10 PM
because the ones available are junk, I can't use them in my bravada because of the poor qc, and they are $10 each last time I got some
Posted By: lilboi
Date Posted: August 02, 2004 at 7:32 PM
I heard they arn't great. I want to be able to have a whole line of leds.
Posted By: lilboi
Date Posted: August 02, 2004 at 7:35 PM
Forward Voltage (V) : 3.2 ~ 3.8 Reverse Current (uA) : <=30 Max Power Dissipation : 80mw Max Continuous Forward Current : 30mA Max Peak Forward Current : 75mA Reverse Voltage : 5~6V
Posted By: xetmes
Date Posted: August 02, 2004 at 7:38 PM
i would do sets of 3 with 120 ohm resistors...
Posted By: lilboi
Date Posted: August 02, 2004 at 8:16 PM
So wire them like (if i wanted 30 leds)
+ _____ [resistor] _____ (+ -) _____ (+ -) ___ (+ -) _____ -
+ _____ [resistor] _____ (+ -) _____ (+ -) ___ (+ -) _____ -
+ _____ [resistor] _____ (+ -) _____ (+ -) ___ (+ -) _____ -
+ _____ [resistor] _____ (+ -) _____ (+ -) ___ (+ -) _____ -
+ _____ [resistor] _____ (+ -) _____ (+ -) ___ (+ -) _____ -
+ _____ [resistor] _____ (+ -) _____ (+ -) ___ (+ -) _____ -
+ _____ [resistor] _____ (+ -) _____ (+ -) ___ (+ -) _____ -
+ _____ [resistor] _____ (+ -) _____ (+ -) ___ (+ -) _____ -
+ _____ [resistor] _____ (+ -) _____ (+ -) ___ (+ -) _____ -
+ _____ [resistor] _____ (+ -) _____ (+ -) ___ (+ -) _____ -
Posted By: xetmes
Date Posted: August 02, 2004 at 8:32 PM
yea like that, you could even use 110, or 100 ohm resistors to be a little brighter...
Posted By: lilboi
Date Posted: August 02, 2004 at 8:55 PM
the leds i've bought are really bright. I like them. Now i have to find a extra set of tail lights so i can do the conversion
Posted By: lilboi
Date Posted: August 02, 2004 at 8:59 PM
BTW, i'm using these for the turn signal. So will i have troublem with electrical? i'm using 30 leds, so will it hyper blink? also does it use more energy then a standard halogen. I'm currently running a 1000watt system, and can't afford more power loss.
Posted By: xetmes
Date Posted: August 02, 2004 at 9:25 PM
30 will draw around a quarter amp (.25 A) what wattage are the bulbs in there? the leds would be equiv current draw of about a 3 W bulb One thing that is commonly done to make them brighter is to flash them, fast enough so the human eye cant tell, that way it can hadle more current in the pulses... i would recommend as many as possible 
Posted By: lilboi
Date Posted: August 04, 2004 at 2:46 AM
3w for 30 leds? How many led's to make it so it doesn't flash. I don't want that hyper bink sh*t.
Posted By: xetmes
Date Posted: August 04, 2004 at 9:52 AM
what size bulb is in there now?
Posted By: lilboi
Date Posted: August 07, 2004 at 6:45 AM
3497
Posted By: xetmes
Date Posted: August 07, 2004 at 8:23 AM
as far as I can tell those are 21 Watts, if you want the same current draw to you do so you could do 70 sets of LEDs (210 lol!) or you could use a resistor to burn off power or you could replace the flasher <-- preferred
Posted By: lilboi
Date Posted: August 08, 2004 at 3:46 AM
flasher?
Posted By: lilboi
Date Posted: August 10, 2004 at 2:16 PM
Posted By: xetmes
Date Posted: August 10, 2004 at 3:05 PM
yea you can do that, use a larger resistor value (like 470 ohms) its just kinda a waste of resistors and power, but if you did that it would only take 70 leds to produce the same current draw...
Posted By: lilboi
Date Posted: August 11, 2004 at 4:36 AM
hmm.... i found a way not to hyper blink. It's called a load equalizer. I'll think about it. What would you suggest?
Posted By: xetmes
Date Posted: August 11, 2004 at 6:52 AM
yea I think load equalizers are just fancy resistive elements, to waste power and draw as much current as incandecent bulbs
Posted By: lilboi
Date Posted: August 11, 2004 at 3:24 PM
So single resistor for each led or one for 3 leds.
Posted By: xetmes
Date Posted: August 11, 2004 at 4:06 PM
ok, ill give you a way to draw the same current using 30 leds... Use 1 resistor per led, each resistor led branch will draw around 25mA, so 30 will draw 0.75A since a 21 watt bulb draws 1.75A we are short an amp, so to draw 1 A... we could put a single resistor in parallel will all the resistor and leds, but that would mean we would need a 12 ohm resistor, further more it would need to be able to handle 12 Watts, quite a bit to use smaller resistors you could put a bunch in parallel, I will assume you are using 1/2 watt resistors.... since P = V(I) and they are in parallel with 12V (assuming the lowest ~12V), V = 12, P= .5... I = (0.5) / (12) = 42mA, therefore maximum these resistors can only handle 42mA, we will assume 40mA so the resistors we need will be 1/2 watt, and must draw 40mA each, since we need to draw 1A we will need.. 1A / 40mA = 25 quite a bit of resistors... now to find the resistance value needed, V = I * R, R = V / I therefore R = 12 / 40mA = 300, so you will need 25, 300 ohm resistors, you can check since the parallel resistance will be 300 / 12 = 12 ohm, so together it is 12ohm and each resistor will be burning off 0.48 Watts... If you use 1W resistors you can use fewer (12 @ 150 ohms) hope that helped...
Posted By: lilboi
Date Posted: August 12, 2004 at 3:19 PM
Damn that's kinda confusing. Alright so if i do get one resistor per led it would be 1/2 watt, 300ohms.
but if i do it in sets of three i only need 120ohms.
Posted By: xetmes
Date Posted: August 12, 2004 at 6:48 PM
sorry it was confusing, i am saying hook up the leds with a single 470 ohm resistor. Then take 25, 300 ohm resistors and solder them all in parallel with the leds/resistors... not elegant and a waste of power but hey it will draw as much as the incandecent...
Posted By: lilboi
Date Posted: August 12, 2004 at 7:57 PM
I rather do it the most efficient way, and buy the load equalizer. So how will i use the least amount of energy for say..... 80 led's (each tail).
Posted By: xetmes
Date Posted: August 12, 2004 at 8:31 PM
I doubt a load equilizer is more efficient, in fact it most likely is just a resistor like a 20 ohm, 10 watt. Problem is that thermal flashers work off heat produced from current draw, there are not that many ways to draw current without using power... least amount of energy for 80 leds using the 3 per row would be 25mA * (80 / 3) = .67A most current for 80 leds using single resistor and led: 25mA * 80 = 2A... too much
Posted By: lilboi
Date Posted: August 12, 2004 at 8:38 PM
so i should go witht he 3 set idea. with 120 ohm resistor?
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