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blue n chrome
Dodge Dakota
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9/16/2003
20:18:26
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 Subject: L.E.D
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Hey I have been putting led's in my air vents and hard wiring them right into my fuse box, I wired them into a 15a cigar lighter and changed the fuse over to 20a just to balance it out, then 4 out of my 8 lights burnt out so i rewired them to just 1 light per vent and another one burnt out , is this because my fuse amperage is too high? or is just a coincidence they are all burning out like this. please help me out this is gettin frusturating.
thanks
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CJ
Dodge Dakota
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9/16/2003
22:24:24
|  RE: L.E.D
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Most likely it is coincidence...the amperage of the fuse doesn't matter...if you put a 20 amp fuse in it just means it will pass up to 20 amps...the L.E.D.s draw x amount of current per bulb...so there is no way to push too much current...by the way...if you are just buying LED's at the store and putting them in then you are most likely putting too much voltage across them...on average an LED is designed to handle .5 to 1.5 volts...not 12 or 14.4...so that would mean that you need to put a resitor in series with them...hope this helps!
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TERRY
Dodge Dakota
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9/17/2003
18:29:58
| RE: L.E.D
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CJ's right you have to run resistors in series with LED's or they will draw too many milliamps and burn themselves out. A LED is only suppose to draw .02 amps for the longest life.
You do not have to increase fuse size they draw very little current.
Different color LED's need different resistors
for example blue LED's have a 3.5 to 4 volt drop so you have to make up for the other 10 volts you are putting to it buy adding a 470 ohm resistor.
I replaced all of my dash light bulbs with LED's and had to solder in a resistor for each one.I now have to make sure that I don't use the dimmer because under voltage will cause high amp draw also.
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blue n chrome
Dodge Dakota
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9/17/2003
23:05:04
| RE: L.E.D
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so what i need to do is splice the wire and add in a resistor???? and just leave the resistor hang bare??? and do i splice the resistor into the positive or negitive wire???
a diagram would be most helpful
also i have a wire spliced into the led wire. because the led wire was not long enough
so where would i put the resistor? maybe in betwwen the splices ??? or???
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blue n chrome
Dodge Dakota
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9/17/2003
23:06:23
| RE: L.E.D
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as well the pack of led's are made for trucks n what not. and it says 12V on the pack so does that make a difference? thanks for all the help thus far
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Daddy-D
*GenIII*
9/18/2003
09:52:49
| RE: L.E.D
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From where did you get the 12V LEDs?
'98 DakSport C/C 3.9 2WD A/T
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TERRY
Dodge Dakota
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9/18/2003
18:28:49
| RE: L.E.D
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Message:
The resistor would have to be on the positive side of the LED . Take 12v pos, cut wire ,splice in resistor to complete the cicuit.
If you run multiple LED's in series,
(that means 12v into first LED out the neg. to the next LED's pos out it's neg. into next LED's pos. and so on just like christmas lights,if one goes out none work because the circuit is broken.)
it will change the resister you need because there is a voltage drop across each LED.
A parallel circuit is like your head lights if one goes out the other still works because they have there own pos. and neg. 12volts from one common source.
A parallel circuit looks like railroad tracks, one rail would be pos. and the other rail would be neg. and the lights would be the RR ties between the rails.
remember to keep amp draw to 25ma(.025amps)max.
The easiest is simply using the right number of LEDs for your supply voltage. Each blue LED gives a voltage drop of 3.6 volts. So, for a 115 volt DC light, you could use 32 blue LEDs in series (115 / 3.6 = 32 +/-) with NO current limiting (they will limit themselves by their inherent voltage drop). Reverse polarity will not damage an LED unless the voltage is very high. It simply will not work, and will not pass current through.
The next easiest is a resistor. The resistor is usually needed since an 'ideal' 3.6 volt source is rarely available. Use Ohms law (Resistance(R)=Voltage(E)/Current(I)) to calculate the value and wattage needed: (R=E/I)
Each blue LED gives a voltage drop of 3.6 volts. for a 12 v light, you can run a maximum of 3 blue LEDs in series at full power (3.6 x 3 = 10.8 volts drop). Subtract this from your supply voltage of 12 volts to get the additional voltage that must be dropped ( 12 - 10.8 = 1.2 volts of additional drop needed). In this case, 1.2 volts of additional drop / .025 amps (25 ma) = 48 ohms. Use the next highest value of resistor available, 50 ohms. You must also be sure the resistor can handle enough current. Volts x Amps = Watts; resistors are rated in watts.
So 12 volts x .025 amps = 0.3 watts. A 1/4 watt resistor would work fine.
This is just an example you need to find out what voltage your alternator is putting out when the truck is running it will be more than 12v mine is 13.7 volts which is about normal,so that is an additional 1.7 v that you have to drop.
The LED's you bought MAY have built in resistors,some do,they usually cost more.
If this is the case you will have to wire them the way the manufacturer recomends.
If you burned them all up go to Radio Shack to get them .A 500 to 1000mcd LED should make a nice glow in your vents. The (2θ1/2)is the viewing angle, wider is usaully better(a 120degree 500mcd LED will put out more light than a 30 degree 1500mcd LED)mcd(millicandella)is the brightness.
I had to grind the domes off my LED's with a dremel and sanding drum for my dash lights to get a softer glow instead of a beam. So you can try that if you can't find wide angle ones.
Resistors are about $0.99 for a five pack .
BTW most LED's are not marked pos. and neg.
so usually the longer leg is the pos. so one side of the resistor would go there the other side of the resistor would go to 12v pos.
resistors don't have a +or- so it dont matter which way you wire it
Hope this helps you,sorry for the long post.
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UFDakota
Dodge Dakota
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9/18/2003
19:45:16
| RE: L.E.D
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DAMN TERRY! i'm sure as hell gonna come to you if i ever have an electrical issue!! :)
-Dan-
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blue n chrome
Dodge Dakota
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9/18/2003
20:00:46
| RE: L.E.D
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ok thanks terry that was very...... fulfilling i got everything i need to know your me new best friend :P thanks again
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TERRY
Dodge Dakota
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9/18/2003
20:09:36
| RE: L.E.D
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I'm cheap, so I gotta be a do it yourselfer, which in turn means you gotta study what you don't know .
can save alot of money that way,or wreck something
spend alot of money,blame no-one but yourself,and learn from your mistakes.
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blue n chrome
Dodge Dakota
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9/18/2003
20:17:47
| RE: L.E.D
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terry perhaps you could give me your email or msn or something because im probably going to have more questions. that is if you dont mind, mine is... jdyoung1127@hotmail.com
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