Inside low-cost LED ac bulbs

Dave_H

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Here are a couple of Home Essentials (from Home Hardware) A19 5000K LED bulbs, 40W (6W) and 60W (9W) equivalent, non-dimmable, 10k hour life. Regular price on these is $2.50-$3.00 each, in 2-packs. Some design similarity, but different enough, 60W is not directly scaled-up from 40W.

40W (top) uses 8 LEDs, having 6 LEDs per package (17.4v). Controller is Chiplight ICL1103 in 3-pin tab package, LED current approx. 30mA. Filter capacitor is 6.8uF which in my crude estimate allows approaching 30v ripple on the rectified dc. How much this impacts light quality is not clear.

60W (bottom) uses 15 LEDs, having 3 LEDs per package (8.6v). Controller is ICL1102 in 8-pin SOIC set to 44mA current. Capacitor is 15uF, ripple estimated roughly 20v.


Dave

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Dave_H

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Ikea in Canada has dropped cost of 40W eq. 2-pack from $1.99 to $1.79 (-10%). In times of inflation I wonder how they manage that.

I think the Ikea bulb uses switching design to allow for easy adaptation to either 110v or 220v markets. The LED drive voltage (around 80vdc) and LED array can stay the same. The input needs to be a bit different i.e. higher voltage rating on capacitor(s) and other minor changes.

Anyway, I picked up some 100W eq. (14W) A19 5000K bulbs from Giant Tiger ("Giant Value"), $2 each in 4-pack. Package says 1300 lumens (not great) but bulbs themselves are marked 1500 Lumens (better). No surprises inside, two linear regulators SM2082EGS in parallel.

Dave
 

Dave_H

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View attachment 48405

Here is inside two more DT LED bulbs, both 40W (4W), round vanity (top) and chandelier (bottom); same design except size of PCB. Linear regulation is using KP18001AESP chip, nothing unusual. LED vf is about 26v, which means 9 series LEDs per package, total vf around 130v.

On the smaller bulb I progressively increased value of current set resistor, from 24 ohms (nominal) to as high as 2000 ohms. At that point, current is around 0.75mA (0.09W) which is low level but works great as a nightlight (though not nearly as bright as jtr's self-built light), and runs absolutely cool so should last a long time.

Dave
Here's a shot of one of the Dollar Tree 40W eq. (4W) E12 bulb with LED current reduced by a factor of about 50. AC input current measures 0.75mA (about 90 milliwatts). As a nightlight it will light up a small room if positioned well. It runs absolutely cold and should hold up for a long time.

The linear regulator set resistor was changed to 2000 ohms. Increasing further had minimal effect as the chip seems to have about 0.4mA leakage with resistor removed.

Note slight damage on collar, from getting the plastic top off; nothing serious, it snapped back together. Anyone not sure about doing this, best to avoid. Potentially lethal voltages are exposed.

Dave
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JoakimFlorence

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It's amazing how well RGB mixes in the plastic bulb to produce cool white.
To be totally fair, that's not really "real" RGB. The R and G in those designs are phosphor covered emitters. So the resulting spectral output of all three combined is probably very similar to a white LED.

Might even expect the CRI to be even a little higher than a normal white LED, since the red and green phosphors have to be farther apart and more distinct. I can make an educated guess and tell you if you looked at this light through a prism you would still see plenty of yellow.
 

JoakimFlorence

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BTW DT Canadian price for LED bulbs has now risen to $2.00.
Of course, at $2.00 it's very likely the government is subsidizing the cost of these bulbs.
The free market price at this time would probably be more like $10 to $12 (if purchased individually from a retailer).

So we can assume the taxpayer (you) is paying the difference.

(There are indeed some 100W equivalent bulbs you can find selling for $2.25 but those are usually sold direct from China and it's probably very doubtful they would even last 9 months, will not be the mainstream brands, will often give off 6-12% less light as well, so not really a true 100W equivalent)
 
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Dave_H

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To be totally fair, that's not really "real" RGB. The R and G in those designs are phosphor covered emitters. So the resulting spectral output of all three combined is probably very similar to a white LED.

Might even expect the CRI to be even a little higher than a normal white LED, since the red and green phosphors have to be farther apart and more distinct. I can make an educated guess and tell you if you looked at this light through a prism you would still see plenty of yellow.
You are correct, red and green are phosphor-converted. This is good in that it should provide higher efficacy for these colours, and makes drivers more uniform; but I prefer the "pure" colours. The PC ones have a distinct pale, somewhat whitish look.

No fancy instruments to measure wavelengths are on hand here, but simple viewing green LED with diffraction surface (CD) shows a fair bit a yellow and some blue. Red is better, mostly red but small amounts of blue, yellow and green visible. Blue of course is rather pure, no conversion.

I have just opened another "RGB" A19 bulb, which contains eight separate white LEDs in addition.

Dave
 

Dave_H

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Of course, at $2.00 it's very likely the government is subsidizing the cost of these bulbs.
The free market price at this time would probably be more like $10 to $12 (if purchased individually from a retailer).

So we can assume the taxpayer (you) is paying the difference.

(There are indeed some 100W equivalent bulbs you can find selling for $2.25 but those are usually sold direct from China and it's probably very doubtful they would even last 9 months, will not be the mainstream brands, will often give off 6-12% less light as well, so not really a true 100W equivalent)
When modern LED bulbs were fairly new, government subsidies here came as coupons at the retailers and were totally visible. They allowed basic 40-60W or small spot bulbs to be sold for around $1 each, but required Energy Star compliance. That was about a decade ago. Subsidies were taken off, and never came back.

Average retail price of 40-60W eq. low-end bulbs here is $2-$3 each in small quantity which I believe allows for reasonable profit. I find it hard to believe this government (or any)needs to subsidize LED bulbs under the table, there is no need to in a matured market with reduced production costs.

Production costing was discussed earlier in this topic. Apart from the Ikea 40W eq. (3.3W) bulbs now down to $1.79 for two, and possibly some Dollar Tree bulbs, I think others are sold above their cost.

Dave
 

JoakimFlorence

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You can ask anyone in the United States if they are seeing 100 Watt equivalents being sold in retail stores for under 4.50 U.S. dollars (6 Canadian dollars). (Especially one that actually puts out a full 1600 lumens @ 2700K)
 

Dave_H

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You can ask anyone in the United States if they are seeing 100 Watt equivalents being sold in retail stores for under 4.50 U.S. dollars (6 Canadian dollars). (Especially one that actually puts out a full 1600 lumens @ 2700K)
As mentioned earlier, in Canada Giant Tiger is selling 100W eq. (2700K and 5000K) bulbs at $8 per 4-pack ($2 each). Dollar Tree is selling 100W eq. for $2 each. To be sure, these are not prime quality, but I have opened up both and see nothing of great concern.

However, they are not 1600 lumens, DT is rated 1500 lumens, the GT bulb says 1300 lumens on the box but the bulbs are stamped 1500 lumens. I am not sure what the big deal is for 1500 v 1600.

I believe Dollar Tree in U.S. is selling 100W equiv. for $2 or less. BTW where are you located?

Dave
 

snakebite

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Anyone chart the lumen depreciation on these bulbs?
I suspect as hot as the funnel (heatsink) gets the dice are running very hot due to drive level and stokes losses.
 

Dave_H

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Anyone chart the lumen depreciation on these bulbs?
I suspect as hot as the funnel (heatsink) gets the dice are running very hot due to drive level and stokes losses.
Yes that would be interesting, lumen degradation and general failure mode statistics. But, there are so many cheaper brands out there to test. Sorry I can't be of much help there, my actual utilization is low and does not begin to approach the stated/expected lifetime of these bulbs, in a reasonable time. Seems it needs some sort of lab setup, or some very dedicated non-professional(s).

Bulb collar getting somewhat hot, but not excessively so, is indication of good heat transfer away from the LEDs, which is good.

Home Depot is now regularly carrying Ecosmart 60W eq. bulbs 2700K and 5000K, for 96c each. No surprise, these are rated only 11k hours.

Dave
 

Dave_H

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Dollar Tree A19/E26 LED bulbs up until not long ago (pre-COVID) were $1.25 each for 40/60/75/100W equivalent, in Canada. Same bulbs are a bit cheaper in U.S. Price started going up and reached $2 each. Since then, two-packs of E12 and E26 candelabra bulbs appeared; they are pretty good.

Now I am seeing two-packs of A19 40-75W eq. priced at $2, so now cheaper than the were originally, in spite of inflation. They appear to be same bulbs, am tempted to buy a pair and open one to check it; but I now have a box full of opened bulbs (which can be reassembled, and all still work!).

Dave
 

Dave_H

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Dollar Tree A19/E26 LED bulbs up until not long ago (pre-COVID) were $1.25 each for 40/60/75/100W equivalent, in Canada. Same bulbs are a bit cheaper in U.S. Price started going up and reached $2 each. Since then, two-packs of E12 and E26 candelabra bulbs appeared; they are pretty good.

Now I am seeing two-packs of A19 40-75W eq. priced at $2, so now cheaper than the were originally, in spite of inflation. They appear to be same bulbs, am tempted to buy a pair and open one to check it; but I now have a box full of opened bulbs (which can be reassembled, and all still work!).

Dave
I just found the 2-pack in one store for $1.50, not sure how long that will last. Some stores still sell single identical bulbs for $2. These are Future Lumen manufacturer.


Dave
 

Dave_H

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I just found the 2-pack in one store for $1.50, not sure how long that will last. Some stores still sell single identical bulbs for $2. These are Future Lumen manufacturer.


Dave
The 75W eq. are OK, contain 15 triple LEDs with vf 8.6v for total around 130v. Linear regulator ICL1102 is rated up to 100mA. Bulb runs hot as expected (12W), efficacy good but not exceptional these days, 1100 lumens = 92 lumens/W. Rated lifetime is 10k hours, not dimmable, no surprise.

Plastic bulb comes off with a little effort, without damage. These bulbs are candidates for running at lower current and intensity for night lights or other low-light usage. This reduces power, yields cooler temperature and extended lifetime, and likely small increase in efficacy. The design would become highly over-margined. For example running this bulb at say 1.5W, the LEDs run at about 0.1W versus 0.8W each. It only requires changing the current set resistor.

Dave
 
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