running 12v LEDs on a 6v system

[ultimatefiend138]

So I'm about midway through making the decision on running LEDs on my cb125s but I've run in to a bit of a problem. All LEDs that I've come across are designed to run on a 12v system but my little bike is 6v. I think it's as simple as changing the resistors for the LEDs but I'm not 100% on that. I'm shooting to get the longest life and the brightest burning LEDs possible. Any suggestions or information?

 

[johnson_steve]

I think it's as simple as changing the resistors for the LEDs but I'm not 100% on that.

You should be; because you are 100% right. there is no such thing as a 12v or 6v LED. I have never seen a LED that required more then 3.4v and most use less then that. The resistors are calculated with Ohm's law to drop the required amount of voltage at the desired amount of current. It's not quite as simple as putting a resistor with 1/2 as much resistance for 1/2 as much voltage. There is some math involved. If you know the specs for the LED in question (forward voltage, desired current.) you can use a LED calculator like this one:

http://led.linear1.org/1led.wiz

otherwise post a close up photo so I can see the LEDs and the bands on the resistor and I'll tell you what resistor to substitute to get optimum life and brightness at 6v.

 

[ultimatefiend138]

Dude that's awesome, I'm thinking about using the taillight off a GSXR but not concrete until I get my seat finished. I'll post some pictures when I get the unit though. Thanks for the info.

 

[johnson_steve]

Glad I could help. The only non LED lighting on my bike is the headlight. Signals, brake light and indicator lights are all leds.

 

[nixon]

Further to this, besides the relevant resistor - do you need a flasher relay (?) to run LED's on a 6v bike?