Adventures with LED light bulbs

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Rikkitic

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#261360 23-Nov-2019 02:10

Do any electronics experimenters here have experience with LED light bulbs? I bought a large number of cheap 15 watt bulbs off AliExpress in different batches and have had nearly all of them fail within days to months. At first I was just going to accept my bad luck and discard the failures, but then I got interested in the reason for so many failures and I started taking them apart.

Most of the Edison bulbs I have looked at have 30 LEDs with very simple power supplies. Most of those with bayonet fittings have only 15 LEDs, though power consumption and light output is the same. They also have transformers and filter circuits.

In most cases, though not all of them, the failures have been due to LEDs burning out. In a few cases the problem seems to lie elsewhere in the driver. It is easy to see where an LED has failed, as dead ones are either completely burned through or have a clearly visible brown spot on them. I cannot replace faulty ones as I am not set up to work on the necessary scale, but I have been able to re-establish the circuit by scraping away the damaged bit and soldering over the remainder. On the bulbs with 30 LEDs, this increases the voltage on each remaining LED by about 0.25 volt. Bulbs I have repaired in this manner seem to work fine, though I haven’t had any running very long yet.

The fact that so many individual LEDs have failed naturally makes me wonder if there could be an issue with our power. We live in an old farmhouse at a rural location but we have never had any problems with any of our other electronics. I am inclined to think these are just very poor quality light bulbs. You get what you pay for and I have not had any issues so far with Philips bulbs I have purchased locally.

As an experiment, I added a 270 ohm resistor to one bulb to compensate for the missing LED. Since so many LED’s are failing, I wonder if it would help to add resistors to all the bulbs to drop the supply voltage a little. What do others think of this idea?

I guess I should mention that I am fully aware of the hazards of working with mains voltages and I take appropriate precautions. I also am closely monitoring any bulbs I have repaired and do not leave them on if I am not in the room.

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jarledb

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#2359591 23-Nov-2019 02:23

I wouldn't want any high voltage (230 volt +) equipment bought from Aliexpress in my own house. Too much of a fire hazard.

Online marketplaces flooded with unsafe electrical appliances

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robjg63

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#2359623 23-Nov-2019 08:32

Are the bulbs rated for 230-240 volts?
I understand we are 230v +/- a certain tolerance. 6% as far as I can see.
So you could have 216 to 243 volts at your place.
China is 220v - if your bulbs aren't up to that extra voltage that could be the issue?

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Mahon

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#2359652 23-Nov-2019 10:31

Rikkitic:

Do any electronics experimenters here have experience with LED light bulbs? I bought a large number of cheap 15 watt bulbs off AliExpress in different batches and have had nearly all of them fail within days to months. At first I was just going to accept my bad luck and discard the failures, but then I got interested in the reason for so many failures and I started taking them apart.

Most of the Edison bulbs I have looked at have 30 LEDs with very simple power supplies. Most of those with bayonet fittings have only 15 LEDs, though power consumption and light output is the same. They also have transformers and filter circuits.

In most cases, though not all of them, the failures have been due to LEDs burning out. In a few cases the problem seems to lie elsewhere in the driver. It is easy to see where an LED has failed, as dead ones are either completely burned through or have a clearly visible brown spot on them. I cannot replace faulty ones as I am not set up to work on the necessary scale, but I have been able to re-establish the circuit by scraping away the damaged bit and soldering over the remainder. On the bulbs with 30 LEDs, this increases the voltage on each remaining LED by about 0.25 volt. Bulbs I have repaired in this manner seem to work fine, though I haven’t had any running very long yet.

The fact that so many individual LEDs have failed naturally makes me wonder if there could be an issue with our power. We live in an old farmhouse at a rural location but we have never had any problems with any of our other electronics. I am inclined to think these are just very poor quality light bulbs. You get what you pay for and I have not had any issues so far with Philips bulbs I have purchased locally.

As an experiment, I added a 270 ohm resistor to one bulb to compensate for the missing LED. Since so many LED’s are failing, I wonder if it would help to add resistors to all the bulbs to drop the supply voltage a little. What do others think of this idea?

I guess I should mention that I am fully aware of the hazards of working with mains voltages and I take appropriate precautions. I also am closely monitoring any bulbs I have repaired and do not leave them on if I am not in the room.

You dont say when you bought them and how much they were each?

Are they actual screw in bulb types or permanently wired in? So many different types of bulbs/fittings and I believe in some cases an electrician is required.

Clearly you have purchased bulbs not suited to NZ conditions.

I know of others who knew what they were purchasing, and have had Aliexpress LED's for years without fault.

Rikkitic

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#2359678 23-Nov-2019 10:39

jarledb:

I wouldn't want any high voltage (230 volt +) equipment bought from Aliexpress in my own house. Too much of a fire hazard.

Online marketplaces flooded with unsafe electrical appliances

It surprises me that a country as up-tight about electrical safety as this one is, allows so much clearly questionable rubbish to be imported in the first place. I am careful with electricity, and I keep a close eye on the things I use, whatever their source. Most vampire devices are on wall switches and get turned off when not needed. I check stuff and make sure it is working properly, as in no arcing noises and that kind of thing. I have smoke alarms in every room. One did save the house when a perfectly ordinary-looking SATA power cable shorted and caught on fire in a computer in another room, but that is the only time anything like that has ever happened.

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Rikkitic

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#2359684 23-Nov-2019 10:58

Mahon:

You dont say when you bought them and how much they were each?

Are they actual screw in bulb types or permanently wired in? So many different types of bulbs/fittings and I believe in some cases an electrician is required.

Clearly you have purchased bulbs not suited to NZ conditions.

I know of others who knew what they were purchasing, and have had Aliexpress LED's for years without fault.

Not sure what you are suggesting. I bought them within the last year. I bought several different batches from different suppliers. I bought some to try at first before committing to larger purchases and they seemed to work okay. These only started to fail after a few months, making it difficult to use the AliExpress disputes mechanism. Others purchased later began failing almost immediately. A few did not work from the beginning or died just after they were switched on, but this in itself is not an unacceptable failure rate. But many have failed after a few weeks, and several after a few months. For LEDs this is certainly not acceptable.

The bulbs are bog-standard light bulbs. If you read my post you would see this. Some had Edison fittings ('screw-in'), others bayonet ('press and twist'). Standard 240-volt Edison bulbs are also referred to as E-27, while the bayonet type are B-22. These are normal standardised fittings. None require hard wiring. Even in New Zealand, electricians are not required to change a light bulb, though how many it takes remains an open question.

Because I bought from different suppliers at different times, and most bulbs seemed to work initially, I no longer remember what I bought from whom, but this is an example. The price is also about what I paid, less than US$3 per bulb.

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Rikkitic

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#2359689 23-Nov-2019 11:16

robjg63: Are the bulbs rated for 230-240 volts?
I understand we are 230v +/- a certain tolerance. 6% as far as I can see.
So you could have 216 to 243 volts at your place.
China is 220v - if your bulbs aren't up to that extra voltage that could be the issue?

Good point. I notice a link I just made in another post does specify 220 volts. I no longer recall which suppliers I actually bought the bulbs from, but they certainly could be 220 volts. I will look some up to check. This difference would probably not matter much to incandescent bulbs, but of course LEDs are another matter.

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Rikkitic

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#2359693 23-Nov-2019 11:34

Rikkitic:

robjg63: Are the bulbs rated for 230-240 volts?
I understand we are 230v +/- a certain tolerance. 6% as far as I can see.
So you could have 216 to 243 volts at your place.
China is 220v - if your bulbs aren't up to that extra voltage that could be the issue?

Good point. I notice a link I just made in another post does specify 220 volts. I no longer recall which suppliers I actually bought the bulbs from, but they certainly could be 220 volts. I will look some up to check. This difference would probably not matter much to incandescent bulbs, but of course LEDs are another matter.

Nope. They're just crap bulbs. I couldn't remember and the order was on a different account but I looked it up and all bulbs I ordered (15 watt) were rated at 240 volts.

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richms

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#2359731 23-Nov-2019 13:35

I have issues with lots I buy locally. Damn things flicker like crazy, some even have part of the 100Hz cycle where they totally go out. Great for inducing headaches, making everything in real life look like a crap video, and for making it impossible to take photos without stripes across them under those lights.

Retailers have no idea about that and are not legally required to put anything about flicker on them but have to put all sorts of other stupid numbers on them for idiots who cant work out that 10 watts for 1000 hours is 10kWh.

Richard rich.ms

Rikkitic

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#2359736 23-Nov-2019 13:59

I haven't had flickering issues just total failures. I am looking into replacing individual SMD LED chips, but I haven't figured out how to unsolder and resolder them. The light bulb heat sink pretty much makes that impossible as far as I can see. I can scrape them clean and bridge them with solder to re-establish the connection, but that is all. Don't know how bypassing one LED in the bulb will affect the lifespan of the others.

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richms

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#2359753 23-Nov-2019 14:36

Rikkitic:

I haven't had flickering issues just total failures. I am looking into replacing individual SMD LED chips, but I haven't figured out how to unsolder and resolder them. The light bulb heat sink pretty much makes that impossible as far as I can see. I can scrape them clean and bridge them with solder to re-establish the connection, but that is all. Don't know how bypassing one LED in the bulb will affect the lifespan of the others.

Will depend if they are current regulated or just use a capacitive dropper. Even the capacitive ones will have most of the drop across that so current will not go up greatly with the reduced voltage across the LEDs by removing one of them.

You can see the osram LED is fine and flicker free, but the ge is a moderate flicker from these pics of them.

I dont have any pics on my camera roll I can scroll back to easily enough of some terrible ones, but that GE basically means if you light your desk with them and take a photo or video, you get those lines. No warning on the box that it was like that and the smaller lower power GE ones are fine - no flicker at all. This one is listed as dimmable which is probably the problem tho.

Richard rich.ms

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#2360086 24-Nov-2019 14:14

Rikkitic:
It surprises me that a country as up-tight about electrical safety as this one is, allows so much clearly questionable rubbish to be imported in the first place.

"Bud, if dynamite was dangerous they wouldn't sell it to an idiot like me".

They don't allow dangerous rubbish to be imported, if you buy it from a local outlet then they will, or at least should, have made sure it's compliant with NZ electrical codes. The fact that you're bypassing the standard checking process to get it direct from Aliexpress is the problem.

It's part of the Universal Rules for Buying S**t:

Never buy anything except linen and crockery from the Warehouse.

Never buy anything from Briscoes or Steven's unless it's a 50% off day.

Never buy anything mains-powered from Aliexpress.

Never buy anything from Noel Leeming or Harvey Norman.

etc