led turn signal resistors

[sofadriver]

Getting ready to install some LED turn signals but I hate to pay 15-20 bucks for the resistor kits. Heck, they're just a couple of 50cent resistors wired parallel to the bulbs, right?

So what's the required resistance?

[suzyj]

About a pound.

Seriously though, the real answer is "it depends", because different bikes have different mechanisms for sensing blown bulbs, with different sensitivities.

A single bulb is 21W. Power is volts x current, or V^2/R. Solving for R gives R = V^2/P, so 12V and 21W gives us something like 6.8 ohms. Two such bulbs can be simulated with a 3.3 ohm resistor. In reality something in between will work well.

It'll get bloody hot though, so don't put it where it's likely to burn you.

[stopintime]

Turn signal bulb is 10 watt, no 

[Raux]

Turn signal bulb is 10 watt, no 

on mine it is

[suzyj]

Turn signal bulb is 10 watt, no  

So it is!

So a 15 ohm (actually 14.4, but who's counting) resistor will provide the same load as a bulb.

[ChrisK]

You can just replace your old flasher, designed for incandescents, with a flasher designed for LED's.

[Speeddog]

You can just replace your old flasher, designed for incandescents, with a flasher designed for LED's.

For his SS, yes.

For his Monster, no, the flasher circuit is in the instrument cluster.

[ChrisK]

Can you just take apart the cluster and replace the flasher? Or is it more complicated than that?

[Speeddog]

Some clusters can be disassembled, some cannot, IIRC 2002-2004 (or so) cannot, later, yes.

But....

It's a surface-mount style circuit board inside.
IMO, it would take a skilled electronics tech to do it, if it was possible.

I'd bet money on suzyj being able to do it.

[stopintime]

Can't remember if this is the correct part, but if it's not it's very close.

Download the data sheet to see how it looks.

http://www.datasheetcatalog.com/datasheets_pdf/V/N/0/5/VN050H(012Y).shtml

[cmejia1978]

my humble opinion: better pay those 15 and be sure they are gonna protect the whole harness rather than pay 500 for a new one... 

[sofadriver]

my humble opinion: better pay those 15 and be sure they are gonna protect the whole harness rather than pay 500 for a new one...  

yeah............... you're right.
a trip to radio shack would probably cost me that much and the store-bought resisters are plug-n-play (i.e. removeable)
guess i'll order them along with these Oberons.
http://www.monsterparts.com/pc/ind0008/Elec-Signals/ind0008.html

nicely priced at Monsterparts.
the black ones should look great on the SS

[suzyj]

Some clusters can be disassembled, some cannot, IIRC 2002-2004 (or so) cannot, later, yes.

But....

It's a surface-mount style circuit board inside.
IMO, it would take a skilled electronics tech to do it, if it was possible.

I'd bet money on suzyj being able to do it.

It's actually incredibly easy. There's a fault pin on the quad high side driver chip that lets the processor know that output current is out of spec. All you have to do is cut the pin (30 seconds work with a scalpel) and all will be good. It's what I've done with my own bike to run Rizoma led indicators.

Alas my bike is in the hands of couriers right now, and I cannot remember the chip part number. I'll check my google+ stream to see if I took a photo...

[suzyj]

Found it!

https://plus.google.com/u/0/photos/114069696154074856835/albums/5815793377770283633/5815793378204115362

The indicator driver chip is right smack in the middle. It's an Infineon BTS711L1 quad protected high side driver.

Cut pins 4 & 8, and no more whingeing about low bulb current.

Oh, according to the data, the open circuit whinge comes on when the output current for each output is less than 200mA. So even if ya don't want to open ya gauges, ya only need 60 Ohms (use 47) across each indicator. Much less wasted heat.

[ungeheuer]

My LED turn signals do some weirdness.

With the motor running, they flash a the correct rate.....

.... but if I flip the turn signal switch with just the ignition on they flash at blown bulb speed  

And even weirder.... they didnt used to do that when I first installed 'em (nope cant remember how many ohms my resistors are).

I'm not stressing about it coz they flash at the correct rate when I really need 'em... but I do wonder if some electronic damage is afoot.