LED wiring - series or parallel?

# Thread: LED wiring - series or parallel?

1. ## LED wiring - series or parallel?

I'm working on an undertail for my bike and wanted to use some LED's for the license plate light.

I can't remember my circuit rules and wanted to know if i should wire up a few LED's in series or parallel along with a resistor?

Thanks

2.

3. i would wire them in parallel, so that the other led will still work in case one of them leds go down

4. Determine the voltage drop / current consumption of your LEDs, and remember V=IR.

If you can wire them in series/parallel (several parallel strings of a few LEDs in series), then use a resistor to limit current to each series string, you should be in good shape.

Example:

(V+)
|
+----/\/\/\/----->|----->|----->|----->|----->|----- (GND)
|
|
+----/\/\/\/----->|----->|----->|----->|----->|----- (GND)

Each LED will have a voltage drop of (for example) 1.3V at a maximum current of 0.025A. Therefore the total voltage drop of the five LEDs in series is 6.5V @ 0.025A. Applying V=IR, we get
(6.5V) = (0.025A) * R
or
R = (6.5V)/(0.025A)

Therefore we want to select a current-limiting resistor of approximately 260 Ohms.

Substitute the numbers for the LEDs you have purchased for your undertail (check the datasheet), and you'll be good to go.

Good luck!

-Matt

5.

6. Methinks jonesboy loved every second of his reply

7. Those electrician's always showing off.

No really that was very informative and easy to understand. Thanks for the reply Jonesboy.

8. I personally would rather use a voltage regulator on the whole system to drop the voltage down for the LEDs. After that you can do everything in parrallel. I try to stay away from series circuits.

-Sandworm

9. Originally posted by Sandworm
I personally would rather use a voltage regulator on the whole system to drop the voltage down for the LEDs. After that you can do everything in parrallel. I try to stay away from series circuits.

-Sandworm
Take advantage of Texas Instrument's free samples

10. how many leds do you want to use?

from my understanding of leds is that they are active devices where their internal resistance change depending on the voltage applied and how much current it takes to light them up.

i think jb is on the right track here. but i would place a resistor for each led while keeping them in parallel.
by placing a current limiting resistor in series with each led, will safeguard that there wouldn't be too much current goin in each led.

11. ever considered litez and boltz, not leds but they do job quite well

12. LEDs will not limit their own current consumption. They'll burn themselves out unless you limit it for them.

While using a voltage regulator to drive a bunch of LEDs in parallel might sound like a pretty great idea, it's not. It doesn't take a great number of LEDs to draw a decent amount of current, and linear regulators will suck that much current from their source pin (10x 0.025A is 0.25A, 40x 0.025A is 1.0A)...

You really want to be sucking 1A out of your electrical system to drive 40 LEDs?

I didn't think so.

You've got 12V - use as many Vs as you can before falling back on As (Is).

-Matt

13. when i did my LP leds...and some of my fellow bikers aswell,

i set it up in series and stuck a resistor in there. all systems are functional and its been almost 9mths.

14. haha i jus tok an LED bulb, attached one hook up wire to one prong, the other hook up wire to the other prong..and each one went to the battery. one marked negative.the other left unmarked as positive. what do you know it works

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