Dutch445
Elite Member
is it true that LED does not attract bugs like incandescent?
LED Lighting Experience?
- Thread starter daveinnh
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schmism
Super Member
is it true that LED does not attract bugs like incandescent?
bugs are attracted by certain wavelengths of light. if the source is putting out wavelengths that are of interest to the bugs, they will fly to it. regardless of what is putting out the light (incandescent, LED, candle flame, HID, CFL) so the only reason why LED would attract less bugs is it is a different wavelength (a less desirable one) which it may or maynot be.
Steve_Miller
Veteran Member
LED lighting is not mastered to the point of mass commercialization yet. The problem being consistent voltage levels and with the newer more powerful, heat is still a major factor. Voltage levels for a typical white/bluish color LED's typical need 3 to 3.6 volts DC and this range will still make a huge diffierference in light output. Typically with this range from my experience is that will get less than half the light output at 3 volts than you will at 3.6 volts, this is why if your power supply and all LED's have one is the critical part of the puzzle. Once you introduce this power supply into the mix it becomes another heat source on top of the LED itself in the package, now put this in a fixture and you have to allow for cooling as electronics do not like heat. If the supply is not regulated (locked at a certain voltage level) then your voltage will swing up or down with the incoming power which is not uncommon in most areas. Sorry to babble but thought some may be interested in a vague insight into LED lighting compared to incandestant lighting which is much much simpler (typical incandesant lights are 5% light and 95% heat) and a lot less efficient.
Steve
Steve
Big Bri
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Steve,
I have to disagree with you, I've got led lights that run 24hrs a day 7 days a week some have been on for more than 2 years. I think the where the problem is in some lights is form the manufacture. I believe a lot of company are putting out cheep led lights. they use fewer led's and bump the voltage to them to make them bright. this is one of the lights we leave on 24/7, not cheep at $139 but they put out some light and last a long time.LEDsplash? 200B | CHAUVET Lighting
now i know this is not what the op needs for his shed but i'm just saying that they do make quality led lights.
eepete
Platinum Member
Let me take a shot at some LED basics.
Leds are diodes, and as such one has to think in currents and not voltages. At a given current, a given LED will put out a certain amount of light. At that current, the voltage drop across the led will change as the temperature of the LED changes. If you put a voltage across a LED and slowly increase it, there will be a point where the current through the LED will increase exponentially. The heat dissipated by the LED also increases with the current.
Small LEDs (currents of 50 mA or less) can often use a simple dropping resistor. This lets you put a range of voltage on there, such as the range often seen from a lead acid battery. The intensity of the led will vary a bit, but from a practical point of view it works. The efficiency is low due to the energy lost in the dropping resistor, but from a practical point of view the entire system draws so little power that the cost savings make it worth it.
Larger LEDs, such as the 1 watt ones, need about a third of an amp. While you can use a dropping resistor, the losses in the resistor start to be a problem. The voltage drop on a LED depends on what the material is, which is also what determines the color of the LED. While and blue LEDs tend to have about 3.3 Volts of drop (with the afore mentioned changes with temperature). Green is about 2V, red is about 1.4 volts.
So with the larger LEDs, electronic circuits are used to create a constant current power supply. There are lots of chips to do this available at reasonable costs, but this is not a DIY project. The chips typically take an input voltage, say from 6 to 30 volts, and output a constant current to drive the LEDs. LEDs are often put in series. For example, you could put 2 or 3 white LEDs in series and run them off of 14 volts. I've used 2 LEDs in series for battery stuff so everything can work all the way down to 11 volts. The key concept here is a constant current so you don't care about the changes in LED voltage with temperature, and the current through the LEDs does not change with the input voltage to the driving circuit.
Driving LEDs from AC (like house voltages) has the same problem as the compact fluorescence. You have to build a power supply into the fixture, and the electronics doesn't like all the trapped heat. Driving LEDs from a DC source of less than 30 volts is much easier since there is just the little driver chip.
The lifetime of LEDs is somewhat subjective. You plot the light output vs. time. At some threshold, often 70% of initial output, you declare the LED to be dead. This number is out in the 100,000 hour range for most LEDs. The problem, and this is why LED lighting is having a hard time taking off, is you have to get rid of the heat the LED makes. Heat is the # one killer of all electronic devices. For every 10 degrees C (18 degrees F) rise in temperature, the LED life is cut in half (this is a rule of thumb so don't flame me here). Getting rid of heat is expensive since it require a metal heatsink, and the means for thermally connecting the LED to the heatsink are often expensive to do from a manufacturing process perspective. So a poor manufacture can cut corners here, run the LED hot, and get 10,000 hours before the LED burns out. Put a 1 year warranty on it and they are good to go. The same poor manufacturer can run the LED at a higher current for more light output, but that higher current means higher temperatures and less life.
LEDs light systems powered by AC have the double whammy of getting rid of both the heat from the LED and from the electronics, often in a form factor and space designed for incandescent such as a ceiling can. If you look at a lot of the commercial LED fixtures (not retrofits for the standard type A "light bulb") you'll see that the rear of them is often a big finned heat sink.
As for efficiency, the design of the LED and the fixture play a role here. Another rule of thumb is that 1 watt of LED is about the same amount of light as 5 watts of incandescent. So a 1 watt LED is about like a long life night light bulb. But to get the 1 watt into the led, the total power consumption (led _plus_ the circuitry) might be in the 1.1 to 1.4 watt range. LEDs in series are popular because you only path the extra power penalty for the constant current supply once even if you're driving a bunch of LEDs.
So LEDs are current devices, and either simple resistors or constant current electronics make them work with constant (or near constant) voltage sources. Heat is the dominant factor in LED life. Efficiency is pretty good, but there is a small price to pay for the electronics. Due to the long life of a correctly engineered LED, unscrupulous or inexperienced manufacturers can scrimp on cost and still have a device with 5x the lifetime of an incandescent light. And in some cases, this might be an OK trade off (like a flashlight).
Finally, LEDs and the electronic driver circuits are semiconductors and as such are very sensitive to voltage spikes. In theory, someone making such a device knows this and will put in spike protection. In practice, for AC stuff be sure you have a whole house surge protector. For DC operated units, try to use a spike protector on the power source or figure out (and this can be impossible) if the manufacturer has included the protection in their LED lights.
So there's some condensed background. The OP asked about LED lights. Done right, they are lower current and longer life and a win. They can save money on installations due to smaller wire sizes needed, and cost less to operate due to lower power - higher efficiency. Drawback is higher initial cost. If you can get something that's not a "light bulb retrofit" package, it has a better chance of being done right.
Another long post, hope it helps....
Pete
Leds are diodes, and as such one has to think in currents and not voltages. At a given current, a given LED will put out a certain amount of light. At that current, the voltage drop across the led will change as the temperature of the LED changes. If you put a voltage across a LED and slowly increase it, there will be a point where the current through the LED will increase exponentially. The heat dissipated by the LED also increases with the current.
Small LEDs (currents of 50 mA or less) can often use a simple dropping resistor. This lets you put a range of voltage on there, such as the range often seen from a lead acid battery. The intensity of the led will vary a bit, but from a practical point of view it works. The efficiency is low due to the energy lost in the dropping resistor, but from a practical point of view the entire system draws so little power that the cost savings make it worth it.
Larger LEDs, such as the 1 watt ones, need about a third of an amp. While you can use a dropping resistor, the losses in the resistor start to be a problem. The voltage drop on a LED depends on what the material is, which is also what determines the color of the LED. While and blue LEDs tend to have about 3.3 Volts of drop (with the afore mentioned changes with temperature). Green is about 2V, red is about 1.4 volts.
So with the larger LEDs, electronic circuits are used to create a constant current power supply. There are lots of chips to do this available at reasonable costs, but this is not a DIY project. The chips typically take an input voltage, say from 6 to 30 volts, and output a constant current to drive the LEDs. LEDs are often put in series. For example, you could put 2 or 3 white LEDs in series and run them off of 14 volts. I've used 2 LEDs in series for battery stuff so everything can work all the way down to 11 volts. The key concept here is a constant current so you don't care about the changes in LED voltage with temperature, and the current through the LEDs does not change with the input voltage to the driving circuit.
Driving LEDs from AC (like house voltages) has the same problem as the compact fluorescence. You have to build a power supply into the fixture, and the electronics doesn't like all the trapped heat. Driving LEDs from a DC source of less than 30 volts is much easier since there is just the little driver chip.
The lifetime of LEDs is somewhat subjective. You plot the light output vs. time. At some threshold, often 70% of initial output, you declare the LED to be dead. This number is out in the 100,000 hour range for most LEDs. The problem, and this is why LED lighting is having a hard time taking off, is you have to get rid of the heat the LED makes. Heat is the # one killer of all electronic devices. For every 10 degrees C (18 degrees F) rise in temperature, the LED life is cut in half (this is a rule of thumb so don't flame me here). Getting rid of heat is expensive since it require a metal heatsink, and the means for thermally connecting the LED to the heatsink are often expensive to do from a manufacturing process perspective. So a poor manufacture can cut corners here, run the LED hot, and get 10,000 hours before the LED burns out. Put a 1 year warranty on it and they are good to go. The same poor manufacturer can run the LED at a higher current for more light output, but that higher current means higher temperatures and less life.
LEDs light systems powered by AC have the double whammy of getting rid of both the heat from the LED and from the electronics, often in a form factor and space designed for incandescent such as a ceiling can. If you look at a lot of the commercial LED fixtures (not retrofits for the standard type A "light bulb") you'll see that the rear of them is often a big finned heat sink.
As for efficiency, the design of the LED and the fixture play a role here. Another rule of thumb is that 1 watt of LED is about the same amount of light as 5 watts of incandescent. So a 1 watt LED is about like a long life night light bulb. But to get the 1 watt into the led, the total power consumption (led _plus_ the circuitry) might be in the 1.1 to 1.4 watt range. LEDs in series are popular because you only path the extra power penalty for the constant current supply once even if you're driving a bunch of LEDs.
So LEDs are current devices, and either simple resistors or constant current electronics make them work with constant (or near constant) voltage sources. Heat is the dominant factor in LED life. Efficiency is pretty good, but there is a small price to pay for the electronics. Due to the long life of a correctly engineered LED, unscrupulous or inexperienced manufacturers can scrimp on cost and still have a device with 5x the lifetime of an incandescent light. And in some cases, this might be an OK trade off (like a flashlight).
Finally, LEDs and the electronic driver circuits are semiconductors and as such are very sensitive to voltage spikes. In theory, someone making such a device knows this and will put in spike protection. In practice, for AC stuff be sure you have a whole house surge protector. For DC operated units, try to use a spike protector on the power source or figure out (and this can be impossible) if the manufacturer has included the protection in their LED lights.
So there's some condensed background. The OP asked about LED lights. Done right, they are lower current and longer life and a win. They can save money on installations due to smaller wire sizes needed, and cost less to operate due to lower power - higher efficiency. Drawback is higher initial cost. If you can get something that's not a "light bulb retrofit" package, it has a better chance of being done right.
Another long post, hope it helps....
Pete
Steve_Miller
Veteran Member
Thanks Pete, Your better at explaining than I.
Brian, I can't explain myself well enough a lot of times but my point is that at $139 this is not going to replace incandescent or compacts for a very long time, yes it is more efficient and longer lasting but the public will never go for it at that price. There is going to be some crossover point where it becomes attractive enough to buy unless Uncle Sam steps in and bans incandescents which is already starting to happen.
Steve
SpringHollow
Elite Member
LVD or Induction Lamps - long life with 5 year warranty, very high efficiency - better than LED or compact fluorescent, start at -40ｰ F, but pricey at $50 (40W with built in ballast). Six bare 40 watt bulbs on the ceiling light up a 24 x 32 x 13 barn quite well.
Ken
Ken
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Great information - I have been wondering what to consider when installing these lights and so far have only heard the good without much of the bad or the ugly. Now I feel like I can design and build an LED installation with a reasonable hope of getting what I wanted and not being disappointed with the results. Thanks guys.
Jim
Jim
