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I need an electrical genius...!

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sullivj
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I need an electrical genius...!

Post by sullivj on Tue 12 Nov 2013, 8:50 pm

OK, I appreciate that no one will see the point, it's probably illegal, no one will like it.....but, my flasher unit has arrived.

I had hoped to be able to make the 3rd brake light in the top box of my CBF 'flash'.

I want to fit in into my top box, which already has a working brake light in it. There's two existing wires, that run into a connection, which only contacts when the lid is shut, and illuminates the brake light.

In advance of cutting the wires, I touched the red on one of the pins, the black on the other pin, and then did the corresponding with the pin receivers. Effectively, applying the 'flasher' in-line. Then I applied the brake and....nothing....!

Am I doing something wrong, or is it just not meant to be?!
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alanesq
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Re: I need an electrical genius...!

Post by alanesq on Wed 13 Nov 2013, 6:50 am

I don't have a spare flasher unit or I would have an experiment but I think you problem will be that the flasher unit is expecting to be driving 2 bulbs (i.e. the current being drawn is not high enough)?
They often stop flashing if one of your indicator bulbs fail for this reason?

btw - I think you would just need to cut the red wire and put the flasher unit across these (i.e. the red wire is the 12v and the bulbs already go to negative via the black)



see this link for more info
http://elektroniki.blogspot.co.uk/2010/09/turn-signal-flasher-unit-et-104.html

how to modify a flasher unit
http://v-ledsblog.com/2010/12/02/how-to-modify-your-flasher-to-work-with-v-leds/

sullivj
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Re: I need an electrical genius...!

Post by sullivj on Wed 13 Nov 2013, 8:39 am

Thanks Alan.  You may well be right about the current.

This is the one I got:

http://www.ebay.co.uk/itm/3212282197...84.m1439.l2649

I'll try and wire it to just the red and see what happens...

Thanks again.
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alanesq
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Re: I need an electrical genius...!

Post by alanesq on Wed 13 Nov 2013, 9:05 am

The link for the ebay item doesn't work for me.

If it doesn't work try putting an extra bulb into the circuit (you may be able to just hold the bulb onto the flasher, it may require 3 or 4 hands ;-) to see if this starts it flashing - if it does then at least you know what the problem is and you can then look at modifying your flasher.

-----

Just had a google:

It looks like there are some different types of flasher unit and I don't know which you have?
If it is an electronic one (rather than the old school bi metalic strip) then I think it will also require the black wire connecting to it after all.
also, it looks like there are 2,3 and 4 pin flasher units.


I wouldn't try anything until we are sure what you have as you may end up damaging the flasher or blowing the fuse on your bike.

BTW - Here are some instructions for modifying a more modern electronic version:
http://www.instructables.com/id/Automotive-electronic-flasher-rate-modification./
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G3o
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Re: I need an electrical genius...!

Post by G3o on Sat 16 Nov 2013, 3:55 pm

@sullivj wrote:OK, I appreciate that no one will see the point, it's probably illegal, no one will like it.....but, my flasher unit has arrived.

I had hoped to be able to make the 3rd brake light in the top box of my CBF 'flash'.

I want to fit in into my top box, which already has a working brake light in it. There's two existing wires, that run into a connection, which only contacts when the lid is shut, and illuminates the brake light.

In advance of cutting the wires, I touched the red on one of the pins, the black on the other pin, and then did the corresponding with the pin receivers. Effectively, applying the 'flasher' in-line. Then I applied the brake and....nothing....!

Am I doing something wrong, or is it just not meant to be?!


Without cutting the wires first you will never get it to flash because even if the flasher unit is doing its job there will still be a constant current going to the brake light. All the flasher unit does is stop and start the current to the light, when all the cables are still in tact it has no means of doing that. 

The ebay link isn't working but flasher units are fairly standard. There is no reason it shouldn't work you just need to get the correct current draw, it is easy enough to fix up with the use of some resistors.
First you need to find out what voltage and wattage the brake light is and what spec the flasher unit is designed for then make up the difference with resistors. Use these formula to work out the data you need for resistance:

I=Current(amps) P=power(watts) V=voltage(volts) R=resistance(ohms)

I=P/V to find the current draw of the brake light.

R=V/I to find the resistance you need to make up for the remainder.

P=VI^2 to find the minimum wattage of the resistor needed

So for example: The flasher unit is designed around  the use of 2 bulb indicators, each bulb being 12v 23w

So the flasher unit wants a total of 24v 46w to work as intended. 

The brake light you have has a single bulb that draws 12v 21w

So you need to make up a difference of 12v 25w

I=P/V; I=25/12; I=2.0

R=V/I; R=12/2; R=6 

P=VI^2; P=12 x 6^2; P=24

So you need a 24w 6ohm resistor to make up the difference.

As a general rule with load resistors you need at least double the minimum required wattage or the resistor will heat up to the point of failure and either blow out or set something on fire! So really you want a 48w 6ohm resistor. The easiest to get your hands on will be 50w 6ohm. 


Hope that helped :]
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G3o
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Re: I need an electrical genius...!

Post by G3o on Sat 16 Nov 2013, 4:59 pm

Just to add, this is exactly the same process as adding resistors for changing to LED indicators

sullivj
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Re: I need an electrical genius...!

Post by sullivj on Sat 16 Nov 2013, 5:38 pm

Thanks very much indeed.

This is the flasher I have:
http://www.ebay.co.uk/itm/Flash-Strobe-Controller-Flasher-Module-for-LED-Brake-Stop-Light-Lamp-v-h9-/321228219724?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4acab1a54c

I should have explained.  There is a sprung pin connector within the top box lid.  These spring pins touched on a corresponding wired in point on the lid, to make the connection when the lid is closed.  I was touching the flasher unit wires on either side of this connection to place the unit 'in-line', without cutting the wires.

I am sure you're right about the resisitence issue.  All I need to do now is find out what wattage the LED brake light is, which isn't easy as it doesn't say on the GIVI instructions.  It runs straight from the 12v - does that give you a clue?

Thanks again - much appreciated.
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G3o
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Re: I need an electrical genius...!

Post by G3o on Sat 16 Nov 2013, 6:02 pm

In that case then i have no clue what so ever! Never seen a flasher relay like that before tbh. I thought you had a normal indicator flasher relay like:
http://www.wardenjp.com/flasher_relay.jpg

Is the brake light LED or bulb? 

if it is LED then you can just get a standard LED flasher relay like:

http://www.ebay.co.uk/itm/12V-Flasher-Relay-For-Motorcycle-Motorbike-LED-Turn-Signal-Indicators-Light-Bulb-/121107735589?pt=UK_Motorcycle_Parts&hash=item1c32956425

Wire it in and away you go, LED lights will be 12v 1w, the flasher unit you have looks like more trouble than it is worth imho :]
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alanesq
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Re: I need an electrical genius...!

Post by alanesq on Sat 16 Nov 2013, 6:22 pm

Yes, that is nothing like the flasher units I was thinking of

The unit you have looks like it should work as long as the light bulb is in the range 10-15 watt.


Last edited by alanesq on Sun 17 Nov 2013, 8:44 am; edited 1 time in total

sullivj
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Re: I need an electrical genius...!

Post by sullivj on Sat 16 Nov 2013, 8:57 pm

Thanks for the link.


Yes, my brake light is a line of LEDs. It's the official GIVI one for the V46 box.


The one I bought did say it was for an LED brake light....?!


I'm thinking it's more trouble than it's worth!
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alanesq
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Re: I need an electrical genius...!

Post by alanesq on Sun 17 Nov 2013, 8:45 am

When you tried it originally, are you sure you had the positive and negative wires the right way round?

sullivj
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Re: I need an electrical genius...!

Post by sullivj on Sun 17 Nov 2013, 8:50 am

Yes, they were. I've since tried it the other way around and just the positive only (with a negative link wire)
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alanesq
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Re: I need an electrical genius...!

Post by alanesq on Sun 17 Nov 2013, 9:23 am

Sounds like it may be a faulty flasher (although I wouldn't mention you have tried it the other way round ;-)

I guess to be sure you would need to try it on another light (maybe try attaching a light to it and holding the wires straight to a battery.
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eternally_troubled
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Re: I need an electrical genius...!

Post by eternally_troubled on Mon 18 Nov 2013, 1:06 pm

Right, I think I understand what is going on, now I've seen the flasher kit.

It looks like an electronic flasher and appears to just have an input and output, so I guess you just put in in-between the bike and the light you want to flash.

For reference the givi box/light that (I think) we are talking about is here:

http://old.itlcanada.com/internal2/instructions/fiches/076e105.pdf


Just to make sure we are all talking about the same thing, I think you should wire it up like this:




You can find out which wires are positive by using a multimeter on the existing wiring or across the bulb.

EDIT: Just in case: RED = positive, BLACK= negative, in my diagram

EDIT EDIT: I bet you can test this by wiring the 'input' side of it across the battery - it should make the LEDs flash.

sullivj
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Re: I need an electrical genius...!

Post by sullivj on Mon 18 Nov 2013, 6:14 pm

Thanks very much for this. I like your diagram.

I did wire it in this way, so I guess the flasher unit must be broken.

Thanks again.

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