Should LED bulbs overheat and disintegrate?

[cdev]

After scanning his videos, I was surprised that none of the bulbs he seemed to review looked like the ones Ive bought here in the US. I probably didnt dig deep enough.

I guess I'll just break out the heavy gloves and try to get the dome off with physical force or if all else fails, break the covers.

I have no desire to use these LED bulbs with mains power any more, however the LEDs which I am pretty sure are for the most part are all still working, (because most of them are just intermittent, not completely nonfunctional) would be quite usable for task lighting if powered and heat sinked appropriately.

Big Clive has done teardowns on lots of LED lights. Given how cheap LED bulbs are nowadays, it can make sense to use multiple run at reduced power (with hacking or a dimmer) so that they run cooler. I would like to see LED bulbs that are dimmable with a knob on the case.

[Leiothrix]

After reading the thread title I can state that I'm really glad that this is not about the struggle to design street lighting 

[cdev]

From the manufacturers and vendors points of view, the observed 'problems' may be a feature and not a bug considering that they could easily last years, so long they would rarely need to be replaced, if they were designed properly.

I can see them saying "where is the profit in that?"

They likely think "there isn't practically any."

Just like drug companies now want costly drugs to manage (newly) costly illnesses, they really don't ever want to cure people anymore. Not unless they can make it really expensive to buy.

[james_s]

The early LED bulbs were designed very well, but they also cost me $40 each. In order to get people to buy them, prices HAD to come down drastically, and naturally that means making some sacrifices, most low cost LED bulbs are rated 15,000 hours instead of 25,000 or more, and they tend to have more restrictions on the sort of fixture they can be used in for airflow reasons.

It's no conspiracy, it's simple economics. How do you sell a bulb for $3 and still make a profit? A proper heatsink alone would consume more than 100% of the BOM budget.

[amyk]

I assume it is just a heat sink and not electrically connected to the innards, but what gives? I thought these things ran cooler [..].

I think about using a 5 volt wall-wart and hooking it up to an array of LEDs and they run cool and still very bright. The wall-wart stays cool too. Why is the bulb so different and why is it not designed to be cool?

Those bulbs are designed to be cheap, as you noticed. Cheap LED bulbs use a capacitive voltage divider - meaning that a lot of energy is wasted as heat, as you noticed already. Examples: http://danyk.cz/ledzar_en.html and https://www.powerelectronictips.com/whats-stuff-capacitive-power-supplies-leds/

On the contrary; a cap dropper does not dissipate any power (besides that caused by the ESR of the cap, which is insignificant) and its simplicity means it will outlast more fancy circuits (which do dissipate power in normal operation); the only reason it's not used for higher power is because of the capacitor size required, as noted in your second link, and the horrible power factor.

[cdev]

If they derated them a bit and added say a 10 cent better heatsink the driver would last 2 or 3 times longer and still deliver acceptable light output.

[james_s]

That 10 cent better heatsink would add at least a dollar to the retail price, and de-rating would require more LEDs to match the lumen output of the incandescent lamps they are meant to replace. Engineers at the major lighting companies have thought of all this, they're not dumb.

[cdev]

They should add a failure rate to the spec, so that people are aware that the lifetime they specify for the bulbs is wildly optimistic, not the real world condition.

It really is a shame they cant be derated somehow, run at a slightly lower voltage perhaps, so they lasted longer. I have LED bulbs in fixtures where they get only very infrequent usage and they still often burn out in a year or less, often just a few months.

[edy]

So are the LED bulbs burning out because of the electronics inside that need to convert the high voltage mains down to what the LED's need? Those electronics are getting cheaper, taking short-cuts and not designed as well, and getting too hot?

Why not build the electronics into the light-switch (and eventually into the actual lighting runs in new houses) to be on a different voltage?

For example, in my kitchen I have a 2-switch panel to control both lights. It is just taking the mains 120V in and then I have a run that goes to the ceiling. Would it not be possible to have the voltage converter in the wall, take 120V down to say 12V (or whatever) and therefore the voltage of the bulb sockets in the ceiling would be 12V and I could use LED bulbs that run on 12V... they would not have as much heat dissipating issues, they would have simpler electronics, they would last longer. Put a single voltage reducer in the actual switch-box and I'll wire up the house with new switches, then the bulbs will never heat up or burn out. The cost of the switches may be less than changing bulbs all the time.

It really is a shame they cant be derated somehow, run at a slightly lower voltage perhaps, so they lasted longer. I have LED bulbs in fixtures where they get only very infrequent usage and they still often burn out in a year or less, often just a few months.

Yes, the so-called "lifetime" is sounding like a marketing scam with a big asterisk and tiny print underneath. There is NO WAY my LED bulbs, none of them so far I tried, lasting anywhere close to the number of hours they claim. 10,000 hours? The bulb is $1.93 CANADIAN:

https://www.canadiantire.ca/en/pdp/noma-led-a19-60w-light-bulbs-soft-white-2-pk-0528077p.html

What exactly is 10,000 hours in real-world usage? If the bulb is kept on 24x7 that's 168 hours per week, so it should last slightly more than 1 year (about 13.5 months). But most people don't use bulbs continuously like that... So I would expect if you have the light on 5 or 6 hours a day, that's 1/4 of the time so it should go closer to 4-5 years! Every LED I've ever owned has "poofed" out well before that. It's a sham!

[coppice]

So are the LED bulbs burning out because of the electronics inside that need to convert the high voltage mains down to what the LED's need? Those electronics are getting cheaper, taking short-cuts and not designed as well, and getting too hot?

I think the opposite is the case. As the strengths and weaknesses of early LED solutions have been seen, newer solutions have been developed which allow both lower cost and lower heat. Most new LED lamps are not getting to the kind of blistering temperatures that even expensive lamps were getting to 5 years ago.

Why not build the electronics into the light-switch (and eventually into the actual lighting runs in new houses) to be on a different voltage?

How exactly would that work? Different lamps require different electronics, based on things like how many LEDs are in the chain. Are you proposing that a lamp replacement would require exchanging a piece in the switch AND a piece in the luminaire? Good luck with that.

[james_s]

They should add a failure rate to the spec, so that people are aware that the lifetime they specify for the bulbs is wildly optimistic, not the real world condition.

It really is a shame they cant be derated somehow, run at a slightly lower voltage perhaps, so they lasted longer. I have LED bulbs in fixtures where they get only very infrequent usage and they still often burn out in a year or less, often just a few months.

They *can* be derated, but that means more parts and higher cost for the same light output. You can already get high quality long life LED bulbs but they cost more money. If yours are failing frequently you are either buying cheap/poorly designed bulbs or using them in ways they were not designed for. I've mentioned previously I changed my whole house over to LED between 2011-2014 and I've had only 4 or 5 failures in that time, all of which were in fully enclosed fixtures despite the bulbs warning against that. The LED bulbs in my outside lights have been running all night, every night since 2011 and they're still as bright as new, zero failures. Those are older Philips bulbs.

[james_s]

The future trend is away from bulbs entirely. In new houses they're building, the lights are integrated fixtures with the LEDs and driver built into an aluminum pcb permanently mounted in the fixture. When the unit fails, you replace the whole thing. Dispensing with the bulb means you can have much more effective cooling at lower cost. The bulbs will stick around a long time for retrofit purposes.

[coppice]

The future trend is away from bulbs entirely. In new houses they're building, the lights are integrated fixtures with the LEDs and driver built into an aluminum pcb permanently mounted in the fixture. When the unit fails, you replace the whole thing. Dispensing with the bulb means you can have much more effective cooling at lower cost. The bulbs will stick around a long time for retrofit purposes.

Having the entire luminaire for cooling really transforms the problem of achieving high reliability. However, economically it only works if these cooler running integrated luminaires genuinely offer high reliability, because the replacement cost of a luminaire is far greater than the cost of a bulb. People need to trust in the reliability to go for integrated luminaires, and its not clear they have much trust right now. They've seen too many early LEDs dim badly or go pop.

[cdev]

Replacing an entire luminare because one LED in a row of 100 goes bad makes no sense either.  What we need are replaceable or even repairable (if people want to do it) LED sub assemblies that have thermal connection to the larger light thats are user replaceable.. Users can smear some thermal grease on the thing. People are intelligent enough to understand this.

Standardized DC driven LED assemblies.

[coppice]

Replacing an entire luminare because one LED in a row of 100 goes bad makes no sense either.  What we need are replaceable or even repairable (if people want to do it) LED sub assemblies.

That depends entirely on the reliability of the product. Typically as we make a product cheaper and more reliable it becomes less repairable. Expect the die by die packaging of the LEDs in most lamps with chains of LEDs to go away. It has already disappeared where it was a big physical liability, such as in the fake filament lamps. It will disappear from most other lamps over time.

[james_s]

No normal person wants to replace an LED or an assembly, everyone just throws it away and buys a new one. People like me will still repair things because we can but most folks will just go buy a new $40 light fixture when it fails 10 years down the road. By that time it will probably be cheaper and more efficient anyway.

Seriously, I'm just not seeing the reliability issues you are. I've had very few LED bulb failures and I know people with integrated fixtures, never seen one fail. There would be no market for replacement modules.