General > General Technical Chat
Explain to me the (de?)-evolution of LED lightbulb technology
MK14:
I suppose if we redesigned lighting circuits from scratch today. We might make them 36V DC, then zero flicker (apart from any voltage regulator and current regulator effects), and minimal electric shock risk, only one household mains to 36V DV converter box needed (standard plug in (into a proper unit, not a mains socket), commodity unit, user replaceable), for all lighting circuits. The LED bulbs would then just be simple (low cost) LED chains (internally), and possibly a resistor or current regulator, inside the bulbs.
Given the low wattage needed by modern LED bulbs, the power and hence currents should be low enough, that the 36V cables wouldn't need to be thick high current ones.
LED bulb life expectancy should improve, because they would have less heat generated inside the bulb, and no need for much extra electronics, on top of the LEDs, except maybe a resistor and/or current regulator.
Summary:
A bit like the florescent tubes, holder. With its internal electronics (ballast), and user replaceable starter. You only need to change the raw tube, not the rest of the electronics.
madires:
--- Quote from: james_s on March 25, 2021, 08:01:23 pm ---They are doing exactly that, but there are billions of existing lamps and light fixtures out there, surely you can't expect everyone to replace all of their light fixtures? There is a lot of vintage/historical/period correct fixtures out there too. LED lighting would take decades longer to catch on if not for readily available retrofit bulbs.
--- End quote ---
Then we have to accept that we'll create more e-junk by using LED bulbs which fail early. Is this better or worse than using incandescent bulbs with a higher power consumption in old lamps?
Kleinstein:
The early LED lamps with still relatively low efficiency had sometime a cooling problem when used at same intensity. It's usually the higher power versions that fail early. Some fixtures just get rather hot and also the CFL lamps could failed early in those. With modern, more efficient LEDs the heat is usually not such a problem any more as the power is soemthing like half of what it was in the early days.
If really in doubt, reduce the intensity and add a second lamp if needed.
One sometimes see new lamps with fix installed LEDs - to make use of the smaller form factor. So it would make sense to get some new smaller standard fixture - still keeping the old E27 / E14 for old lamps.
TimNJ:
--- Quote from: madires on March 25, 2021, 08:24:08 pm ---
--- Quote from: james_s on March 25, 2021, 08:01:23 pm ---They are doing exactly that, but there are billions of existing lamps and light fixtures out there, surely you can't expect everyone to replace all of their light fixtures? There is a lot of vintage/historical/period correct fixtures out there too. LED lighting would take decades longer to catch on if not for readily available retrofit bulbs.
--- End quote ---
Then we have to accept that we'll create more e-junk by using LED bulbs which fail early. Is this better or worse than using incandescent bulbs with a higher power consumption in old lamps?
--- End quote ---
I'm sure this has been studied and thought about many times, probably even on this forum alone. Still, here's my own thought experiment
Supposing an 800lm LED lightbulb lasts 6 years running at 5 hours a day. Over six years the energy usage is about 55KWh. Let's say the life span is about 10,000 hours, after which you have to throw it out and replace it.
If you used a 60W incandescent lamp for the same duration and hours per day, the energy usage is about 660KWh. Let's generously say it's lifespan is about 2,000 hours, so you'd need to replace it 5 times over this time.
The missing pieces are: The energy input required to make each type of bulb and the environmental impact of each bulb when it's chucked in a landfill. I don't think you can put the latter in terms of energy...although maybe you can think of it as the energy required by some poor future human society to un-****-up the world the previous generations left them.
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Total Energy (LED) = 55KWh + (Energy to Make/Dispose LED * 1)
Total Energy (Incandescent) = 660KWh + (Energy to Make/Dispose Incandescent * 5)
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Energy to Make/Dispose LED < 605KHh + (Energy to Make/Dispose Incandescent * 5)
So, naively, it makes environmental sense to use an LED as long as the energy it takes to make one LED bulb is less than 605KWh + the energy it takes to make and dispose 5 incandescent bulbs. And I have no idea how to gauge how much energy is required to make an LED bulb. But, it seems like LED bulbs should make environmental sense.
TimNJ:
Is the fact that you can get an LED lightbulb for $5USD a reflection of the amount of energy it takes to make it? At that price, is it reasonable to think that it really doesn't take that much energy to make one?
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