running 12 volt LED lights on 6 volts

Like the title says, can I run a 12 volt LED taillight on only 6 volts? I've read that the lights will be dimmer, but still work. I want to use a cat eye lens for my cafe racer project, but I couldn't find anything for 6 volt. I'll have to assume that the lights I've looked at are in series. Most adds don't list the voltage, resistance, etc...of the individual LEDs themselves, so ballpark answers will have to do.

Another option is to stay with incandescent. Again 6 volt is a problem. If I replaced the 12v bulb with a 6v bulb, would I encounter any issues assuming the contact points of the two different bulbs are the same?

I hate electrons so treat me like a 5 year old.

You can't put a 12v bulb on a 6v tail light, the bulb will be barely visible at night and invisible during the day. With an incandescent bulb light output and voltage do not have a linear relationship. When operated at 1/2 the designed voltage a 12v bulb will not just be 1/2 as bright but will be many times dimmer. Here is an example of measured light output vs voltage on a 12v incandescent headlight bulb

Anndd now after I actually read what you wrote you never intended to put a 12v bulb in a 6v system... my bad

And to actually answer your question... yes 12v LEDs will be much dimmer or possibly wont wont work at all if ran on 6v. Too dim to safely use as tail light.

And if the contacts line up a 6v bulb will work fine in a 12v housing

This is what I was looking at.

http://www.ebay.com/itm/CAT-EYE-MOTORCYCLE-TAILLIGHT-BRAKE-LIGHT-CUSTOM-CRUISER-BIKE-LICENSE-PLATE-MOUNT-/161036146448?pt=Motorcycles_Parts_Accessories&hash=item257e809710&vxp=mtr

or

http://www.ebay.com/itm/UNIVERSAL-LED-MOTORCYCLE-CAT-EYE-TAIL-BRAKE-PLATE-LIGHT-RUNNING-LIGHTS-BRACKET-/161035207473?pt=Motorcycles_Parts_Accessories&hash=item257e724331&vxp=mtr

I did find a 6 volt specific LED tail. But its in Germany. I might just bit the bullet and order that.

http://www.ebay.com/itm/Clear-but-red-lighting-mini-LED-tail-light-for-6V-use-6-Volt-very-bright/360438928907?_trksid=p2045573.m2042&_trkparms=aid%3D111000%26algo%3DREC.CURRENT%26ao%3D1%26asc%3D27%26meid%3D8069010679298765103%26pid%3D100033%26prg%3D1011%26rk%3D1%26sd%3D360438928907%26

You can find a lot of 6v specific lighting at Treatland.tv (place I get all my moped parts from).

Worst case, get a 6V to 12V inverter to drive the light.

Oh joy! I totally forgot about Treatland.

What do you think about this one?

https://www.treatland.tv/oval-clear-LED-tail-light-p/oval-led-clear-tail-light.htm

A customer review says that he used it successfully with a 6v Tomos. Or should I stay with incandescents like this one?

https://www.treatland.tv/alien-eye-tail-light-p/alien-eye-tail-light.htm

Is it really that hard or impossible to build the project at 12v?

That being said I am sure that out there somewhere there are LEDs designed to work with 6 volt systems. After all, there is a thriving restoration market...

And another note, most LEDs run on something like 3 volts. Resistors are used to to get the voltage down to where it is needed for the LED. Maybe you could fab your own lamps...

Scott

LED's are current devices, not voltage.
There is an inherent voltage drop Vf determined by the particular semiconductor material and fabrication used, usually between 2-3 Volts, and also an additional voltage drop from the amount of current flowing through the device.
Often the LED's are connected in series, the number in a string limited by how many multiples of Vf it takes to equal the supply voltage.
Bottom line, an LED is almost NEVER directly connected to a voltage source without some kind of current limiting device.
LED's that are packaged into plug-in replacement lamp forms will already have these current limiting devices built in.
A resistor is a cheap and easy way to limit the current to the desired range, but there are integrated circuits specifically for delivering constant current, and or delivering constant light output from strings of LEDS.

The bad thing I've seen is that most of these light ads have little to no information as to the construction within. Hard to do anything but guess.

erohslc said:

LED's are current devices, not voltage.
There is an inherent voltage drop Vf determined by the particular semiconductor material and fabrication used, usually between 2-3 Volts, and also an additional voltage drop from the amount of current flowing through the device.
Often the LED's are connected in series, the number in a string limited by how many multiples of Vf it takes to equal the supply voltage.
Bottom line, an LED is almost NEVER directly connected to a voltage source without some kind of current limiting device.
LED's that are packaged into plug-in replacement lamp forms will already have these current limiting devices built in.
A resistor is a cheap and easy way to limit the current to the desired range, but there are integrated circuits specifically for delivering constant current, and or delivering constant light output from strings of LEDS.

I am think of using an led lamp on my old motorcycle. The generator normally has a filament lamp that is bright if the charging circuit is not working. As the level of charge in the battery goes up or the rpms go up the lamp will dim indicating the charging circuit is working. Will an led function properly in this application?  Thanks 

In reply to erohslc :

Thank God somebody in this thread understands how electricity works. I was just about to come in here and correct a whole bunch of stupid. 
https://www.superbrightleds.com/cat/led-light-bulbs-universal-finder/filter/Voltage,6,100,4204:

go here. Gets what's intended for the system. 

What is the voltage for USB ?

There are a lot of LED lights that work on USB .....

In reply to _ :

As far as I can tell, not one of those 6 bulbs from your link are intended for a headlight.

californiamilleghia said:

What is the voltage for USB ?

There are a lot of LED lights that work on USB .....

5vdc