LED's for turn signals and brake lights

[fauslyfox110]

I keep seeing conflicting information online with regards to LED's and their reduction in energy toll on the early gold wings. What energy savings can I see by swapping tail lights, and turn signals on a naked 79 gl1000 with LEDS? I want to run speakers so I'm looking to lower the energy rain from incandescents.

Thanks for the help guys

[Sidecar Bob]

If some of this sounds familiar it is because most of it comes from stuff I posted in various places in the last couple of years:

Based on my own experiences, I don't recommend putting coloured LEDs in coloured lenses.

LEDs produce more light per unit of electrical power because almost all of the power used in the actual LED is converted into light, as opposed to something less than 10% for incandescents (the other 90+% becomes heat). The problem with many LED bulb replacements is that, because of the design of most commonly available LEDs, they tend to have a narrow radiation pattern. In other words, while incandescent bulbs produce a sphere of light, LEDs produce a narrow beam.

This can be useful in some applications. For example, I much prefer LEDs in the headlights of my model trains. It is next to impossible to produce a beam of light like the sealed beam or bulb in reflector headlight of a real train with an incandescent. They don't make bulbs small enough to put a scale sized reflector behind and painting the back half of a grain of wheat or grain of rice bulb silver just doesn't cut it. But LEDs shine a beam down the tracks and reflect off of buildings & scenery just like the real thing. And on top of that, train speed is controlled by track voltage so unless you install special circuitry, incandescents are really dim when the train is moving slowly and don't get bright enough until the train is moving way to fast, but LEDs produce a good amount of light from fairly low track voltages.

Incandescent bulbs produce broad spectrum light so lenses designed for them can filter just about any frequency that is anywhere near close to the desired colour and still be acceptable. For example, some tail light lenses are more tomato red (orangeish) while others are more cherry red (verging on purplish) but both will meet the requirement for a "red" tail light. Since you are filtering out most of the light, you are also reducing the efficiency yet again.

The colour of light produced by an LED, on the other hand, is determined by the material the diode junction is made of (eg. gallium arsenide diodes produce red light) and is limited to a very narrow band of frequencies. This means that the frequency of the lens must be pretty close to the frequency of the LED if you want the light to be very bright. For example, if you put LEDs that produce 625nm red light (they rate them by bandwidth) behind a red tail light lens that filters 670nm it won't exactly dazzle the driver behind you. For all practical purposes the only way to find out if it will work well is to set up two lenses in the same place at the same time, one with the standard incandescent and one with the LED, and compare them.

When I put the sidecar on Mr.H I bought a pair of rectangular trailer lights in the hope that I could mount their boards inside the bike's original tail light and a matching Honda light that I could mount on the sidecar. I hooked up one Honda light with incandescents, one of the trailer lights with its original lens and one of the LED boards sitting inside the other Honda lens and stood back about 15-20 feet to look. The trailer light was by far the brightest, although its lens actually looks darker than the Honda lenses. The LED board in the Honda lens was the dimmest. As much as I would have preferred to have matching Honda lights with LEDs in them on the bike and sidecar, Mr.H has the trailer lights in their original, somewhat industrial looking housings and with their original lenses. When safety is involved, form must always come in second to function. Eccles has a set of square LED trailer lights. Note that the Superflux LEDs used in the trailer lights (& almost all tail lights in new cars) are much brighter and have much have a much wider viewing angles than your typical 3mm or 5mm epoxy lens LEDs.

There are lots of really nice LED bike tail lights for sale on eBay that could be installed on your bike easily. Of course, I discovered this after I had bought & installed LED trailer lights on both of my machines.

If you do decide to go with bulb replacements, make sure you get white ones. Because they produce a broad spectrum (white light is a mixture of a whole range of frequencies) they will work with any lens designed for use with an incandescent. Because the lens wastes most of the light, they will use more current for the amount of light that the lens passes than LEDs that match the lens would but it will still be a huge amount less than incandescents would need.

An even better solution would be to buy 12V white LED panels. I used 12V white 48 LED panels (source: eBay) in a pair of old Suzuki turn signals on the back of Eccles and in the fairing's original left signal and a trailer signal on the front of the sidecar (+ 24 LED panels for the running lights in the front ones).

I have been told that my brake lights and turn signals are almost painfully bright. There can be no excuse for not noticing them.

BTW: I mentioned in the first paragraph that actual LEDs are pretty efficient, but that isn't the whole story. The forward conducting junction voltage of an LED is between 0.7V and 2.6V, depending on the junction material (& colour). If any greater voltage is applied to the LED the smoke will get out. Since the LED needs a resistor to limit the current anyway, the normal way of dropping the voltage is to calculate the resistor value by dividing the excess voltage by the current you want to run the LED at. This means that in a single LED single resistor circuit (2.6V LED, 14V supply) you typically waste more than 4 times what the LED actually uses.
Manufacturers of LED panels have access to LEDs that are close enough to identical that they can string several in series (usually 4 or 5 2.6V on a 14V supply) and use a smaller resistor so that the resistor now wastes much less power.

[fauslyfox110]

Thanks for this very detailed response, I will take your words into good consideration. I ordered a pair of white LED's I will see how they look compared to the incancesdents. From what I understand, if I elect to change my turn signals too, I would need to get an electronic flash relay correct?

[Sidecar Bob]

I already had a 2 terminal electronic type in the 650 when I changed to LEDs and it worked OK with them as long as I still had the bulbs in the instrument panel. When I replaced the panel (now all LED) the current was too low to make that flasher work so I had to change to a 3 terminal type.

When I did the 'Wing I changed to a 3 terminal flasher right away.

BTW: You should also consider upgrading your headlight to an HID http://ngwclub.com/forum/viewtopic.php?f=1&t=24396