Electrical Help

1. ## Electrical Help

I know that the answer to this is going to be painfully obvious once I hear it but I still can't puzzle it out on my own.
I want to dim my taillights so my brake-lights appear brighter when they come on. My first thought was to put a resistor in series with the bulb but I haven't tried it yet. I really don't want to increase drain on the charging system but I will if I have to in order to make this work.
Thanks,
Grant

2.

3. putting a resistor in series won't drain battery. however, make sure it's in the tail light wire and not the brake wire, otherwise you brakes lights will dim too.

also, the bulb filament may not like the lack of voltage and the inrush current of the brake lamp may shorten life of bulb.

careful not to short anything else out too.

4. thanks. Any idea what value of resistor I'm looking at here?

5. sourcing a different wattage light bulb here would be the sensible choice.

6. I agree with fish antlers. Check with the better parts places and Automarine Electric. If they can't help then the resistor would be doable. Or you could use a power diode or two to cut down the voltage at the light. In the forward conducting direction diodes drop the voltage by 0.6 to 0.7 volts depending on how much current is being drawn. That way the start up of the filament isn't damped by a resistance.... not that it's a big deal anyway.

It only takes a volt or two less voltage to cut the wattage and thus the light by quite a bit.

I believe that brake lights are 12/25 watts. So the running light is about 12 ohms when brightly lit (this is important as the resistance of the filament changes as the current changes. It's low when dark and gets higher as it glows). I'd go for something like a 2 to 4 ohm resistor. If you buy a pack of 5 or 6 one ohm / one watt resistors then you can build up a final resistor by connecting them in series. Also these will get warm, not hot, but warm to the touch. Making it up using more than one will keep any single resistor from getting too hot. You're spreading out the heat over more area. Bend the leads together so they are mechanically ties and solder and cover the final product with some heat shrink tubing after you test the results. It's hard to say how much resistance you want as the light will change quite a bit with the first couple and then not as much with more. And then there's the way it looks through the red plastic lens. It's very subjective so it's easier to just experiment by adding one at a time until it looks good. You may end up with 2 or you may end up with 5.

You can get the parts from a number of places but Ridd electronics, Intek or Active are all good places to start. They are all near first and Boundry. And RPE is also a good spot and they are in behind the Canadian Tire store on Lougheed between Boundry and Willingdon.

7. There are standards that tail lights MUST adhere to for brightness etc. These are legal requirements and they are established for your own safety. "Dimming" the tail light to make the brake light appear brighter is a dangerous thing to do. THis means that at night your running light will be dimmer and therefore you will be harder to see. If you "dim" your tail light and you are in an accident, you could very well negate your insurance as your bike wouldnt conform to DOT standards. I know you may have other mods, but they do looks for properly werking lights, and a horn as the very basics.

What you REALLY want to do is make the brake lite BRIGHTER, making it more visible.

You could replace the current tungensten bulbs with LEDS, which would solve your problem altogether, as they are considerable brighter.

8. LEDs are still questionable replacments. They are "brighter", but thier beam tends to be much more directional. Remember to mount several at slightly different angles.

The legal issue about 'dimming' a light is another typicaly canadian problem. I am not sure, but I think that the national saftey rules give a min wattage for a taillight bulb. Any LED system will be below this wattage. -> illegal? If you put a resistor in-line then you are not really changing the stated wattage of the bulb. The regs do not stipulate a min voltage. The voltage ALL sportbikes tends to drop at idle-> less wattage from lights. -> illegal to idle?

-Sandworm

9. I just bought LED'S for my 99 R6. They are a direct replacement for the 1157 bulbs. They look way better and are a lot brighter when braking. http://www.superbrightleds.com

10. uh.... I'll have to disagree with you Sandworm, you're just plain wrong here...... DOT standards are not only based on wattage, but also on brightness. All engine have voltage that varies, however they also have correct this variance with this little thing called a "voltage regulator"... without this all of yer electrics would be toast....

re: LEDs..... LEDs may be directional, but they are going to be installed in a tail light lens housing, which is a diffuser, therefore they will no longer be "directional". There are many aftermarket LED replaements for tungsten lamps. They have to be DOT approved or else you wouldnt see them on say, a bus or a new R1.

Come on.. you said you're a lighting guy. This is basic stuff !

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