LED Flasher Question...

[XJOK2PLAY]

I have a Vetter trunk on my XJ, as most of you know. On the back, it has had the 2 round standard fixtures replaced w/ 2- 2" tall x 4" long LED light fixtures... each w/ 4 led's/ fixture. They are the kind that have both brake & tail lights.

Today, I decided to purchase & add an LED flasher, and wire it on the brake side, so that my brake lights would flash on the trunk for an attention getter.
(Stock brake light on the fender would stay on normally.)
It's wired correctly, but now it seems the flasher's not going to work because the load demand of the 2 light fixtures does not exceed the 1 amp minimum required to make it flash. (Range of the flasher says 1 amp min. to 10 amps max.)

Does anyone have any ideas how to increase the load demand to make it flash w/o adding a bunch of extra LED lights to the circuit? (I have no place to put any more, not to mention cost.)

I can't even imagine how many LED's I'd have to have just to make a 1 amp load!

Whaddya guys think... a lost cause? Flasher & connector cost me $23.

Suggestions are much appreciated! Thanks.
Bob

[Montreux_Blue]

My little led blinkers work, just blink fast.

[crazy steve]

Pick up a 15 ohm resistor and hook one end to the wire going to the lights and the other end to ground. Get at least a 25 watt rated one or you'll burn it up. It will get hot, so mount it with that in mind; attaching it to a piece of aluminum for a heat sink would be a good idea.

'78E original owner.

[Larrym]

Satisficing the Problem

XJOK2PLAY,

If I understand you correctly, you wish to make the pair of led lights flash while your standard/OEM brakelight remains constant.

Just an option to consider:

If you were to connect the OEM brakelight into the same flashing unit you would have more than enough current draw to make the flasher work:

P=I times E

OEM brakelight =27 watts so 27 divided by 14.4 equals 1.87 ampreres.

Maybe not exactly what you wanted but an excellent example of satisficing: sacrificing what you really wanted for something you can be satisfied with.

OFC this all depends on whether brakelights according to the law have to be constant/non-flashing. I dunno about that..

HTH.

[mxmikie]

napa auto parts grote led flasher part #44891

[XJOK2PLAY]

Hey guys....

Great suggestions, and I do appreciate them.

I wondered if some form of resistance added to the circuit would do the trick, Steve. Thanks! How hot are we talking? Hot enough it would need to be exposed to air to cool it? Wanted to conceal all of it in the trunk if possible.

Larry: I might could rig up a socket w/ a 1157 and keep it inside the trunk or something... if nothing else, I can test it that way and confirm that more load is needed to make it flash. Thanks! I'll give that a test tomorrow.

MXMikie: the one I bought today says it's for LED's, but has to have at least 1 amp draw... do you know if the one you're giving the Napa # for has a minimum draw requirement? Obviously, the 2 LED fixtures I have don't pull much... even though 1 amp's not much... it takes several LED's to equal that.

Thanks guys!
Bob

[Rasputin]

Just wondering if you could utilize a product like this one. Mostly thinking out loud

http://www.signaldynamics.com/products/Modules/xp.asp

[XJOK2PLAY]

I like that! That's pretty cool....

I see that this particular unit says it will work either LED, incandescent, or both! I'm now wondering if the flasher I have will work an incandescent along w/ the LED's?? If it would, I could add the bike's 1157 brake light in on the circuit, which would add the extra load... but I bet it won't.

Any takers?

I may try it tomorrow just to see.

[crazy steve]

I wondered if some form of resistance added to the circuit would do the trick, Steve. Thanks! How hot are we talking? Hot enough it would need to be exposed to air to cool it? Wanted to conceal all of it in the trunk if possible.

Thanks guys!
Bob

A 15 ohm resistor will put about a 1.1 amp load on the flasher. If you have trouble finding one that size or find you want more load (if it flashes real fast, it's not enough), a bit less will be fine too. If you go below 10 ohms, expect more heat. You can get a wire-wound ceramic one for $3-4 at radio trash.

How hot? That will depend on how long the brake light is on, but it shouldn't set anything on fire. It may get hot enough to melt plastic though, so a heat sink is a bit of insurance. Inside the trunk, I'd put a cover over it too for protection of both the resistor and any contents. Most places that have the resistors will also have cheap little aluminum 'project boxes' that would be perfect to house this. I'll be mildly surprised if the whole works costs you $10 (it has been a while since I bought this stuff...).

'78E original owner

[XJOK2PLAY]

napa auto parts grote led flasher part #44891

Checked my part number this morning... that's the one I've got!

Called the auto parts store where I bought it... he looked it up & says it will also work on incandescent as well... so looks like I'll be trying to add the bike's 1157 in the flasher circuit as well... that should provide enough load then to make it flash. Let ya guys know how it turns out. Thanks for the suggestions!
Bob

[Larrym]

Razzle Dazzle.

If the flash rate is high enough then the LEDs will truly flash on and off to get that extra attention while the incandescent OEM brakelight won't really have the time to turn off/cool down before it turns on again.

So it just may work out that the OEM light will sorta "Pulse" in brightness instead of an on/off effect.

Any way to adjust the flash rate of the unit??

[CatatonicBug]

The Vetter trunk started out with 4 lights, not 2. If you have 2 large lights now, someone cut the housing to make them fit. I have seen that done, so it's not a bad thing.

From my experience, the LED lights will not work unless the bulbs in the stock brake light on the fender have been switched to LEDs as well. Since the load is being pulled across the whole circuit, all the bulbs need to pull the load equally to allow the bightness to change (from running to brake light). I assume whatever unit you are looking to install allows the load to remain intact while flashing, so the stock brake light is not affected by the change in load.

If it were me, I would just wire the trunk lights to work as running/brake lights. The bulb in the trunk has to be capable of the dual brightness though. Autozone sells the 1157 LED bulbs that will work in the stock fender light fixture.

[XJOK2PLAY]

OK, Guys... quick update.

Tonight after work, I picked up an 1157 light fixture, and wired it in the switchleg side of my LED flasher...

Bingo! Success! I now have flashing LED's.

The extra load of the 1157 was enough to make the flasher work.
It flashes @ a rate of around 60 flashes per minute when the bike's running...
just right.

Thanks to all for your ideas.
Regards,
Bob

[cywelchjr]

Sounds great. The trunk came with 4 round lights. The ones you have sound like what Craig suggests if the originals are no good as they can't be replaced. Mine had one ground lug gone, fortunately I was able to solder a ground wire to that light and they all work now (all LED of course).

I also finally put a disconnect into my harness that I had made since mine didn't come with one. Now I could take it off and just have a luggage rack if I wanted to without having to cut wires.

[Crazcnuk]

A true LED flasher doesn't care what the load is.

I am guessing you bought one of the 'fake' electronic flashers. They are actually a hybrid of the electro-mechanical flashers and require a certain load to work.

The LED flashers, I have, I bought with the LED bulbs. They will flash, at the same speed, regardless of how many bulbs you have in the circuit.