is there a limit as to how meny led's i can have in 1 series strand...heres my led specs..
Green
current 20
brightness 5000
max voltage 4.0
veiwing angle 30
wave leigth 525

any help would be appreciated

If the voltage of each led is 4.0 volts and the car voltage is 12 volts then
12 divided by 4 = 3
therefore if you can put 3 leds in series

close, but not true...

3 would be the maximum that he could run, as 4.0V is the MAX Voltage the LED can handle.

all you would loose by instaling more than 3 would be, possibly, some brightness.

you could put in as many as you want, but add them in one at a time or you will not have any idea how bright they will be when you get a string of like 20 together.






Injection is nice but id rather be BLOWN!

think you mean 14 volts but i wont get pick on that ...you think id loose quite a bit of like doing 6-8?

wheres that edit button i've heard rumors of....i ment loose quite a bit of light with 8-10 led's....as apposed to the 5

Yes there is... to determine how many LED's you can put in series, you will need the spec's (forward voltage, and current)... which you have listed above.

Go to this site, use 13.8 as the input voltage, and enjoy

(there is an error on that page though, the resistor should go before the LED's)

If you were to run 6-8 in series, they may not even light up. LED's require a minimum voltage to light.

Here's the results of your LED's (BTW, wavelength and viewing angle don't calculate into the voltage, however you do want an LED with a decent viewing angle)

If you want more, why not hook them up in parallel? Won't that work?

If there is a resistor on each LED, are you still limited to a max per line? I thought (like Wild Weasel said) that if you wired them in parallel with their own resisters the number didn't matter.


____________________________________________________
2002 2.2L -Base Model- (not for long) Black Cavalier

And... for the record... I know absolutely nothing about this. I'm just asking the question because I think it might be possible.

Don't worry Weasel, I got it covered...

If you hook them up in parallel, each with a resistor, then yeah, the sky's the limit as to how many you can hook up. The catch is this... the fewer you have in a series, in this case 1, the larger resistor you will need (therefore upping the overall cost)

Using your specs:



Now, this isn't so bad, come to think of it. 1/2 watt resistors are about the same price as 1/4 watt ones.

Using the specs from red LED's, though

30 mA
2v forward voltage



1W resistors are a little more pricey, it would be more cost effective to go series/parallel, as in the following example with your green LED specs



Let me know if any of this doesn't quite make sense...

you can hook as many as you want in parallel and use only 1 resistor!
if you put 1 resistor to drop the cussent from 12v to 4v and then after that you hook in parallel, so each led will get 4v.
Its easier like that!

Not quite.

The resistor may blow or you will need a hefty resistor (2+ watts) and that can get into the igher price range ($10 / resistor versus .05 / resistor)... That's a lot of wattage that would need to be disappated by the resistor. 80mW per LED for green


I can always test that theory though, I got plenty of spare LED's/resistors lying around

yeah, more watts would be needed....

So for cost effectiveness, stick with 1 resistor per LED...

Went to go solder up the test board and wouldnt ya know it, I'm outta solder...

ok im under the influence if i used the correct amount of led's i didnt need a resistor, is that true? cause now im thinking if i didnt have one...then the first led would be at the mercey of all 14v

halfJ99 (Nik) wrote:ok im under the influence if i used the correct amount of led's i didnt need a resistor, is that true? cause now im thinking if i didnt have one...then the first led would be at the mercey of all 14v

Nope, all of the LED's will see the same voltage. Thinking the first one see's 14v, second one 10v and so on is incorrect. I wish I knew of a good way to explain it but I don't, they'll all see the some voltage.

No. They draw such a low amprage it really doesnt matter. They should not be seeing a voltage drop due to the amount of usage. Hook em up in parrellel or series whatever you like. I worked with LED emergency lights and they are not picky.

Quote:

ok im under the influence if i used the correct amount of led's i didnt need a resistor, is that true? cause now im thinking if i didnt have one...then the first led would be at the mercey of all 14v

The first part is correct. If you have 6 LED's in series and they are rated at 2v each, you don't need a resistor.

The second part is the circuit is seen as a whole, so the entire strand is at the mercy of the 14v

ok so with my 4v max...im gonna hoop up 4led's to each strand...making 16v of course..., i wont need a resistor...and they will be ok ?, thats what i got from all this

You are correct.

However, they will be dimmer than 3 with a resistor.

thats fine...their going into vents, they will be bright enough for that