LED indicators and flash rate

[Quiff Wichard]

OK

u know I put LED's on

man said wouldnt pass MOT at fast flash rate so

- resistors-

OK- so all works fine at right speed............until:

I put my lights on.. if I have full lights on they dim and ig engine isnt on at all they dont even work and when rngine running and if they are on and I brake-- as you do at a junction(oops) they dim??))))

so@ I know its a voltage thing with LEDS- but I am a numpty !!!..


have I wired them wrong?.. ? i dont think so as the MOT man passed it as is but said I could do with a seperate relay -

not the one that is in use that is multi functional but keep that in and then bypass it for the indicators- he was goin on about orange wire for a suzuki or summat-!

I think they are ok but I worry that when I stationary (is that paper clips or standing still I never know if its an a or an e ) with my brake on- they dim.....

just how dim they are at night I know not- i will try tonite- may still be very visible in the dark..! and I dont (I know I should) ride in the day with my headlights on as I have blue covers !....


so any advise.. any electricians can provide me with the reason.!

i was well chuffed that I soldered all the resistors on myself(with help via msn from peter henry) ... and now it seems I may have made a faux pas!

NB- excuse my typing- friday is my longest day - stats at 5am !!... and I just got in and had 2 cans of bitter .. mmmmmmmmmmm

sounds like a short on the negative, check to see if you have a bare wire or two wires touching or a wire contacting the frame. failing that i would image you have a broken wire.

good luck

had issues with the maplin resistors but once i put the HG ones on everything was fine. Which did you use?

[Quiff Wichard]

Used HG ones..

but confess that my soldering skills are rudimentary !!!

[Quiff Wichard]

Originally Posted by BigDog

sounds like a short on the negative, check to see if you have a bare wire or two wires touching or a wire contacting the frame. failing that i would image you have a broken wire.

good luck

simple as that-
??

nowt to do with the volts etc??

Hi Quif,
I'm a sparky.

First question...are you sure this fault did not exist before you changed over to the LED indicators?
Do your other lights dim under any conditions?

It could be a poor connection to negative, (ground), somewhere on the bike. Make sure the connections at the resistor, indicators and battery posts are all good.

Make sure you insulate the connections at the resistors with plenty of electricains tape.

Make sure the size of the resistor is 21 watts or higher and roughly 7 Ohms.

Let me know how you get on, this shouldn't be too big a problem to fix!



The principal behind the whole reistor thing is simple really. Your flasher unit is designed to work at a certain flash rate when the pair of bulbs in operation are OK. If the bulb brakes, this changes the amount of current drawn in the circuit, and alters the flash rate letting you know that you have an indicator out. So its obvious that changing the load away from what the flasher expects is going to change the flash rate.

So if we ignore the load from the LED units, as they take almost no power compared to the original units 21 watts, things get simpler still. All we need to do is pop in a resistor for each LED which will draw roughly the same amount of power as the old indicators.


So the original indicators were 21 watt, and any resistor we use will need to be at least 21 watts as well. But what size of resistor?

R=V/I I=P/V

I=21/12 =1.75

R=12/1.75=6.85 Ohms

The nearest size of resistor you can buy is 7 Ohms 21 watts.

Wire/solder/crimp one resistor in "parallel" with each of your new indicators.
Jobs a good un.

What do I mean by wire in parallel? At each indicator unit you will have two wires going in to the unit. Connect either of the wires to either end of the resistor, and connect the other cable to the other end of the resistor. Remember your adding the resistor to the existing circuit, so your not cutting anything out, and you shouldn't have any wires left floating about in mid air!

[Quiff Wichard]

THAT is ace advice-
I gonn a print it off.
cheers for taking the time...

I am sure others will benefit too.....

see- I wish i had been a sparky or bricky or got a trade now !!


I will let you know how i go on..

wont be today - it is bouncing rain here at the moment !.. and i have no garage!

[BillyC]

Originally Posted by Philbo

Wire/solder/crimp one resistor in "parallel" with each of your new indicators.
Jobs a good un.

This was my thought: that you'd placed the resistors in series with the indicators. This will affect the voltage that they're allowed to draw from the circuit. This is worth noting as LED's have an activation voltage, below which, they will not illuminate at all.

Worth checking!

[Quiff Wichard]

it is in parrallel............ must be something like a bad connection-.. super advice-

Originally Posted by Philbo

The nearest size of resistor you can buy is 7 Ohms 21 watts.

Hi Philbo - this is what I figured was needed as well but when I dropped into Maplins asking after such a relatively high wattage resistor, they looked at me like I'd asked them for a left-handed elephant....

Where would I buy such a resistor (especially as a one - well 4 - off)?

Thanks

Mat