L.E.Ds

[Draco87]

Quick question I have leds fitted to my r6 front indicators have a resistor each side and flash work correctly. However I've fitted an integrated taillight with indicators do I need to fit a resistor or two for the taillight and if so what size. The symptoms are when I turn the indicator on with the side lights they flash as normal but so is the red light but nothing noticeable to the person behind. Any help would be great thanks[/i]
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1992 Yamaha SR125, 2005 Honda XR125, 1998 Yamaha XJ600S, 2000, 2004 Yamaha R6, 2002 Yamaha Fazer, 2004 Honda CBR

[Peperami]

Hi Draco87,

It is normal for LED's to have a resistor in series though sometimes this can be integral to the assembly. Some designs have a solid-state driver built-in to supply the LED's with the correct current so no additional components are required.

Without more information on the particular assembly you have its difficult to give a precise answer. As for the value of any such series resistor it very much depends on the safe-current the LED assembly is designed for.

Did you receive any technical info with the LED's which you can share? We really need more information in order to answer your questions.

Regards,

Peperami.

[Draco87]

Unfortunately, I had no information for them, only specs are that it was advertised as 12v which is standard. But it is a solid built in unit so unsure if it has built in resistor. The only I can do is take a couple of pictures but not sure how that would help. The option I could do is to try and fit my existing resistor to the rear and see it stops the flashing of the red light
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1992 Yamaha SR125, 2005 Honda XR125, 1998 Yamaha XJ600S, 2000, 2004 Yamaha R6, 2002 Yamaha Fazer, 2004 Honda CBR

[stinkwheel]

So the tail light is flashing with the indicators?

LEDs do stuff like that sometimes because they'll run on such low currents.

It suggests you have a poor earth connection somewhere or there is a poorly insulated track on the PCB the lighting unit is attached to allowing crossover of current.

When you hooked up the light unit, how many wires did it have? Was there a seperate earth for the stop/tail and flasher parts?

I have LED bulbs in my clocks and some of them glow when it's raining, this is a tiny current leaking across the wet surface in the back of the clocks.

The resistors pepperami is on about will already be fitted so your LED light clusters "plug and play" at 12V so don't worry about that. The ones that were fitted al;ng wth your front flashers will have been ballast resistors to increase the current load so your indicator relay flashes.

The whole idea of fitting ballast resistors with LED flashers so they work with the original relay strikes me as a bit of a nonsense. When I've done it, I use an electronic flasher relay and no ballast, otherwise they use no less power than the normal bulbs.

In fairness, I've gone right off LED taillights. They seem to be no more reliable, they are very narrow angle and therefore difficult to see, more expensive and it is often difficult to differentiate the stop from the tail. They are also prone to nonsense like you describe above due to tiny current leaks about the place that wouldn't bother an incandescent bulb.

I only use LED bulbs in places where the bulb is a pain in the arse to get at (eg clocks) or on bikes with pathetic charging systems. I've shitcanned all the LED tail lght bulbs I had and put filament ones back in.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Draco87]