LEDs

[mraf]

I was bleeding all the fluids on the 86 during the Monsoon rains that we have been having and noticed that 1 of my LEDs was dim. I had another one and replaced it. On further inspection I have 2 more dim ones and 1 that is completely out. What gives? I was under the impression that the lifespan of LEDs was quite a few hours of operation. Mine might have a total of 30 hours on them. Is anyone else experiencing low lifetime on their LEDs.

[BuddyRich]

LEds ? Single leds ? Is there a current limiting resistor ? Biggest cause to burn out an led is over current.

[flb_78]

You can't overcurrent an electrical item, just over voltage it.

 

Most likely it's the solder joints to the board. It happens sometimes with high end LED's and it's pretty common in low end LED's.

 

I saw it alot in trucks. Trucklite and Grote brand were very bright while cheaper "no-name" LED's would be dimmer and actually have LED's "burn-out" across the board. I could smack em with a screwdriver and and watch the LEDs flicker.

[BuddyRich]

You can't overcurrent an electrical item, just over voltage it.

 

 

If you don't know anything about electronics or ohm's law its best not to say anything. You certainly don't with that statement.

[flb_78]

really? How do you overcurrent something?

 

Electrical items draw what they need, you can't force amperage into something.

 

The reason for installing a resistor on LED's is so that turn signals won't blink at an accelerated rate.

[BuddyRich]

RIGHT !

To much current (amps) occurs when there is to little resistance to current flow at the specified voltage. Hence the reason your fuses are marked in amps . Lets put it this way. Your headlamp is running at 12vdc. 15A fuse. The resistance the filament has to current flow causes it to glow and all works well. You take the same circuit and short across the filament (no resistance to current flow now) and bang, you blow the fuse because of too much current flow , still at 12vdc. Electronics 101...

Edited July 6, 2009 by BuddyRich

[ArcsSparks]

you can raise current by upping the voltage or redusing the resistance. Leds have a limiting resistor (already said) if that resistor is to small (low in value) or shorted the flow of electron will be higher which is "over current" causing early failure

[flb_78]

OK, let's start over.

 

First, we need to know what kind of LEDs we are discussing.

 

I am under the assumption that we are using a prebuilt board designed to be used in a 12v application.

[Guest tx2sturgis]

Yall are getting caught up in terminology. The term 'overcurrent' is normally understood to mean that too much current went thru a component because there was no limiting device present or working, OR that there was too much voltage applied and as a result, higher than normal current flowed, and damage occured. High voltage, by itself, doesnt do any damage, its the high current that results from higher voltage ( or no limiting device) that does the damage to a component.

[Guest tx2sturgis]

I was bleeding all the fluids on the 86 during the Monsoon rains that we have been having and noticed that 1 of my LEDs was dim. I had another one and replaced it. On further inspection I have 2 more dim ones and 1 that is completely out. What gives? I was under the impression that the lifespan of LEDs was quite a few hours of operation. Mine might have a total of 30 hours on them. Is anyone else experiencing low lifetime on their LEDs.

 

LED's normally have a lifespan of thousands of hours. High brightness LEDS are in the 10,000 hour range, and normal LEDs are rated at about 100,000 hours. But something you said makes me ask this question:

 

Monsoons? So things are VERY wet? Check that LED board carefully to see if there is ANY evidence of water intrusion. It may have gotten some water and road crud inside and caused some LED's to run too bright, because of shorting across the load resistors. Of course that would cause the LED's to burn too bright and then burn out.

 

 

Now if your lamp is completely dry and sealed then its more likely a failure of the LEDs due to the limiting resistors having too small a value, and allowing too much current to flow and burn the LED's out, OR , poor quality LED's.

 

Edited July 6, 2009 by tx2sturgis

[flb_78]

that's why I was wondering if this was a commercially built unit designed for 12v applications or if is a handful of diodes from Radio Shack.

 

If it's a commercially built unit designed to run on 12 volts already, then no additional resistors should be needed. The ones I've mostly dealt with were prebuilt plug and play units and were direct replacements for incandescent bulbs.

 

If what we're talking about is running down to Radio Shack and buying a handful of loose diodes and mounting them on the bike, then yeah, you'll need resistors because most commercially available loose diodes are rated at 20ma@5v and a 12 volt load will overcurrent it.

[Guest tx2sturgis]

that's why I was wondering if this was a commercially built unit designed for 12v applications or if is a handful of diodes from Radio Shack.

 

If it's a commercially built unit designed to run on 12 volts already, then no additional resistors should be needed. The ones I've mostly dealt with were prebuilt plug and play units and were direct replacements for incandescent bulbs.

 

If what we're talking about is running down to Radio Shack and buying a handful of loose diodes and mounting them on the bike, then yeah, you'll need resistors because most commercially available loose diodes are rated at 20ma@5v and a 12 volt load will overcurrent it.

 

I also assumed it was a commercially built 12v LED board. Since he said he got 30 hours out of them, I have to assume it was not a handful of 3 volt diodes hooked up directly to 12 volts, since they would have a life of less than a few seconds if run directly on 12 volts.

[Moped]

tx2 sturgis gave a good explanation , flb 78 knew what he was saying also just didn' go into detail. The current draw is a function of the resistance of the device and the voltage applied. The led resistance stays the same so to increase the voltage (flb78) is the only way to destroy the device by over current your ohms law reference to current, (current drawn is the voltage divided by the resistance of device. Led's in general operate at 2 to 3.5 volts in general. The normal current draw is 20 milliamps. The variabiles of voltage on led's is determined by the color and size of led. Simply stated your bike's voltage is 12 volts. Apply that voltage to led and it becomes a flash bulb. You now put a resistor in series with the led to limit the current to the 20 mils. The resistor block's or drop's the voltage down to that 2 to 3.5 volt depending on the led's to get it to only draw the 20 mils. If the resistance is calculated wrong, to high resistance will produce to low voltage dimming led. To low will increase voltage and depending on the over voltage will either destroy the led or decrease the hours it works.

[StarQ]

Did anyone answer the guy's question about his dirty, low down, low life LED's? LOL

[StarQ]

How about the noise emitting diode? When connected to a 120v source it makes a loud pop - once.

 

I also assumed it was a commercially built 12v LED board. Since he said he got 30 hours out of them, I have to assume it was not a handful of 3 volt diodes hooked up directly to 12 volts, since they would have a life of less than a few seconds if run directly on 12 volts.

[flb_78]

Did anyone answer the guy's question about his dirty, low down, low life LED's? LOL

 

To answer the original question, we need to know what type of LED it is,

 

Yes, I have seen LEDs fail in a short period of time, usually from shoddy manufacturing.

[Guest tx2sturgis]

How about the noise emitting diode? When connected to a 120v source it makes a loud pop - once.

 

 

We used do that with small electrolytic capacitors...electric fireworks!

 

 

[mraf]

Finally getting back on here to see the replies. Thanks for the input. After reading everything I've come to the conclusion that they were cheaply made. Hence the rather quick demise. They came with resistors already installed but were not really expensive {cheap}. I'll replace them, no big deal. Another rainy day project. The last LED lights I installed keep beat with any music near or on the bike. Can't turn them on going down the road though. It makes the light look as if it has a short in the wiring. Looks cool though when the music's on sitting.