LEDs starting to flicker.. are they bad?

I have 64 LEDs (super white 3.5V max rated) hooked up in my car... running 13.2V, not more.

The LEDs are 4 in series and each series strip are paralleled. So I have 16 strips paralleled. No resistor is being used because each one gets about 3.2V and lower. Each LED is rated 3.5V max.

Anyways.. I've ran these LEDs for 2 weeks, 2 hours each day.

This morning, I noticed that 1 of my serie strip is flickering. I kept on flickering for 1 hour, so I turned it off and turned it back on, now another strip is flickering!! Total of 8 LEDs flickering.

What does this flickering mean? Is it about to die? Is only 1 led in the strip causing the the whole strip to flicker? These leds are rated 10,000 hours.

help!

thanks.

Flickering or strobing??? Strobing is definitely bad LED(s). Unprotected LEDs can and do go bad. Not sure if yours are or not, but, it does not sound good.

Thanks for the reply.

They are actually strobing. Giving that hypnotizing effect.
If one in the series is strobing, will it cause the whole series to strobe? Or is my case just coincident?

My 64 leds are unprotected, because I thought that since it will never hit 3.5V max, I wouldn't need any resistors or anything else.

My current setup is 4 (rated 3.5V max) in series, 16 of those series are parallel. Total 64 leds. What should be the correct way to wire 64 leds to keep them from going bad if using 13.2V? Am I suppose to wire all 64 leds in parallel with each led having it's own resistor = 64 leds + 64 resistors?

I am paranoid that my all my leds will go down. =(

Thanks.

Just to let you know what I am up to... I am working on this cluster project. It only used 2 bulbs for each gauge, and decided to ditch the bulbs and do a full LED conversion....

Before picture is the yellow/dimmed stock gauges...


After I installed alot of LEDs...


Completed and though everything is okay for 2 weeks till the strobing started....

Take out the kit and start testing individual leds to find out which ones are crapping out, and replace as necessary. /ubbthreads/images/graemlins/banghead.gif
It's not unusual for vehicle voltage to near 15-16 volts while running!
This would be kinda pushin it for "4 series-ed "T5 leds
What brand of leds are you using? /ubbthreads/images/graemlins/smoker5.gif

My vote would be to go with some luxeon3 leds (4 series-ed)
These will need some heatsinking, but are otherwise well underdriven and should live a long time and are really f'n bright. /ubbthreads/images/graemlins/wink.gif
Go here for info on them; www.luxeonstar.com

I actually bought a bulk packs of LEDs and drill and hacked my gauge cluster and put in individual leds in there....

I bought my LEDs from ebay - Hong Kong dude. Yea, I know "I get what I paid for", but I honestly think something else is wrong instead of the cheap leds.

The specs for my leds are 3mm, 3.3v normal, 3.5V max 4000mcd/5000mcd max.

If my car is infact blowing more Volts than I thought, then can I use 10,000 mcd leds with the same specs at above, and put a resistor at the power line to use the same configuration, and have the same light output?

It took me over 40 hours doing this project for it to crap out on me... if my wiring is indeed bad, what would you suggest how I should wire my large amounts of leds? What's the best way to wire them? I've heard the best way is to solder each led in parallel with each led having it's own resistor.. is this true? If it is the best way I will do it. If I only need to add a resistor to my power line to my current wiring configuration.. that will be great.

Thanks all for the help.

BTW, I know that my LEDs are cheap, but I am doing large mounts of led wiring, so I don't want to fry up expensive leds yet. So I am using cheap leds for experiments 1st. I get 100 white leds for $25, and I've fried plenty so it's good I start with cheap ones.

I just found out I posted in the incorrect forum topic. Is there anyone (moderator?) that could move my post to the correct place, please?

Thanks~!

You should add a one or two ohm resistor in series just in case. It will not cause much of a power loss at all, but may help your LEDs from drawing too much current. Each and every LED has a slightly different forward voltage. A resistor can help smooth out the variations.

Also double-check your solder joints...

A flickering LED usually means the LED is overdriven, and the wire bond (very thin gold wire inside the LED) has become broken from too much current through the LED, and then begins an expansion/contraction cycle that results in flickering or strobing. If the bad LED is in a series string with others, the others will also flicker or strobe in unison with the bad one.

Automotive electrical systems can output as much as 16 volts when the motor is running; running these series arrays without resistors on that electrical system is probably what killed them.

Insert a 470 ohm (color code: yellow, violet, brown stripes on the resistor body) 1/2 watt resistor in series with each series string.
This will limit LED current to 30mA even when the engine's revved up, and prevent that flickering or strobing from occurring again.

Hope this information is helpful.

You can try adding just a few ohms of resistance to get your current setup to just.... work the way you wanted.
I would recommend using loudspeaker grade 5-10 watt resistors just to be safe and they too are cheap.
You will lose just a little brightness, but it shouldn't be enough to boo-hoo over.
good luck. /ubbthreads/images/graemlins/smile.gif

If you have a series amp meter, or access to one, it can help you "fine tune" how much resistance to add in order to keep your current of electricity within spec for the leds,
(20 or so ma).
These are easy to find under $50 nowadays.

You can get a nice cheap DVM from Harbor Freight for under $5

Definitely under $50, WOW!!
No excuse not to have one now huh? /ubbthreads/images/graemlins/smile.gif

All,
information provided has be very helpful! I like to thank everyone and will try out what have been suggested.

I think my LEDs are dying soon, so I might as well replace it all and put resistors in each series.

3rd shift - I think I will underdrive the LEDs for now to see how I like them. I'll see later if I'd like to optimize and use my LEDs to the fullest... I'll come ask you. Thanks!

This forum has been most helpful.

BTW, I have an amp meter, but only know the basics of it. It has alot of options on the dial, but I only know how to use it for current/volts/resistance. Basic stuff. My father is an electrician, so I 'sorta' picked up things from him. I also took some electrical classes, but found it to be too frustrating to me so I switched to Bio-Chem. I ace the electrical classes but it takes me much much much more thinking on things that shouldn't require much thinking. So I only know average things about electrical stuff. I install alarm systems, headlghts/fog lights, and stereo systems, but those are not sensitive or as complicated as LEDs or small components!

Thanks all for having patience with this newbie!

what about using capacitators to even out the voltage spikes?

An alternating current "loop" amp meter won't work.
If it has a series test lead "DC" mode, that is what you are after.
Good luck.

I was replying to volkracing,
my bad..

[ QUOTE ]
chamenos said:
what about using capacitators to even out the voltage spikes?

[/ QUOTE ]

That sounds like a good idea since I am using the leds in the car. Now I got to whip out my old ECET books to see how they are calculated /ubbthreads/images/graemlins/eek.gif and placement...

3rd_shift, its ok /ubbthreads/images/graemlins/smile.gif

volkracing, if the capacitators work well enough you might not even need the resistors /ubbthreads/images/graemlins/grin.gif