LED lightbulbs question

[natr0n]

When it comes to home lightbulbs why do they output more heat than they are rated for ?

I got some 60 watt equivalent daylight bulbs rated at 9 actual watts.

When you touch the base of these thing you can cook an eggs on them.

 

[FordGT90Concept]

The base of them is basically an AC/DC power supply. If you want them to last a long time, they have to keep cool (can't put them in a light fixture that has a cover preventing air flow, for example).

The LED lights I measured ended up drawing significantly more power than the label on the package claims they should. This was also the case with CFL.

 

[TheLostSwede]

Actually, it's not just the AC/DC conversion that's a problem when it comes to heat, as modern, efficient AC/DC converters (much like PC power supplies) can easily have an efficiency rating of 90% or more, which means not a lot is wasted in heat.

The bigger heat source is actually the LED's themselves, that's why they're mounted on a metal backed PCB, which is very different from the fibre glass PCB you'll find inside a PC for example. This is done to help dissipate the heat from the individual LED's so they don't overheat and fail. The LED PCB is then usually mounted on an aluminium "holder" that then connects to the outer housing of the LED bulb, which is again made out of metal to help dissipate the heat.

The issue is that something like a 9W LED packs in quite a lot of LED's on a comparatively small surface area and this produces a lot of heat that needs to go somewhere. Normally, the fewer LED's inside the bulb, the more heat each LED outputs. Different manufacturers have different means of solving this problem, although by now, most LED bulbs have smooth outsides, although some higher-power bulbs still have large heatsinks as their outside surface, as did most LED bulbs in the early days.

There have even been attempts at making liquid cooled LED bulbs, but these were complex and costly and as such simply weren't competitive in the market. Here's an example of such a bulb being taken apart. The guy that posted that video has a lot of LED bulb teardowns.

 

[jboydgolfer]

I guess It depends on what kind you use. The type I have don't get warm at all ,they don't get anywhere near as warm as a standard lightbulb. I don't know if it's due to the design, or the way the casing is built ,but you could holding your bare hand and you never know it had been plugged in.

Again I don't know if mine are different from yours I'm sure they make many different types

I suppose the actual LED bulb would be inside of this "bulb". FWIW, these bulbs I have go inside of the glass dome mounted on the ceiling. They've been running for over 2 1/2 years now and I've never had to change them. I had to clean the glass domes about a week ago , & to do so ,I had to remove the bulbs, and they were no different than room temperature. Got em at homedepot, pretty cheap i have the 7watt, 10 watt, and 14 or something

 

[natr0n]

I guess It depends on what kind you use. The type I have don't get warm at all ,they don't get anywhere near as warm as a standard lightbulb. I don't know if it's due to the design, or the way the casing is built ,but you could holding your bare hand and you never know it had been plugged in.

Again I don't know if mine are different from yours I'm sure they make many different types

View attachment 97704

I suppose the actual LED bulb would be inside of this "bulb"

mine look just like those.

 

[jboydgolfer]

mine look just like those.

It may be that yours have a casing that is really thermally conductive ,so that the heat generated inside is felt prominently outside. if it becomes a problem ,just head over to Home Depot or Lowes or something ,they normally have them on sale & you can grab some cheap. For what it's worth, the Doma on the bulb in the picture I posted above is plastic as is the casing below it. There may be some type of insulation to avoid burning your hand, because I had to use gloves when I replaced the standard bulbs with these years back

 

[eidairaman1]

mine look just like those.

Being a walmart brand vs the brand jboydgolfer used can make all the difference.

 

[Sasqui]

I'm about 80% done switching over from CFLs to LED at my place. Kill a watt typically shows 8-9 watts for most 60w equivalent Less. Some get warmer than others but I think it really comes down to the heat dissipation characteristics. Some of the better quality bulbs have heatsink fins at the base, others don't. It's the ones that don't that get warmer, but certainly none hot enough to burn or cook an egg!

 

[rtwjunkie]

I’ve completely switched all bulbs in the house. Yes, they do put out heat still, but it is nowhere near the head that standard bulbs output. So despite some heat, it makes for a cooler house in the summer.

 

[natr0n]

Being a walmart brand vs the brand jboydgolfer used can make all the difference.

True.
In the meantime when I dont turn on the bulb; I use a simple desk led light 4-6 watts light up my whole room when pointed at ceiling doesnt ever get warm either.

 

[qubit]

The LED lights I measured ended up drawing significantly more power than the label on the package claims they should. This was also the case with CFL.

I'm surprised that they can get away with that. Could there have been an error in your measurement perhaps, especially regarding power factor?

To everyone: even if they don't draw more than 9W or so, they can still get very hot if there's nowhere for the heat to go.

 

[DeathtoGnomes]

Being a walmart brand vs the brand jboydgolfer used can make all the difference.

yep, like anything else in this world, you get what you pay for, buying cheap you get cheap quality.

 

[Sasqui]

I'm surprised that they can get away with that. Could there have been an error in your measurement perhaps, especially regarding power factor?

That is surprising. All the bulbs I've tested are either spot on or 0.5 W lower than the rating on the box.

 

[FordGT90Concept]

Actually, it's not just the AC/DC conversion that's a problem when it comes to heat, as modern, efficient AC/DC converters (much like PC power supplies) can easily have an efficiency rating of 90% or more, which means not a lot is wasted in heat.

If PFC which is expensive. The cheap LED lights are not, hence the substantial heat at the base. They're probably about 70% efficient so 30% of of the wattage consumed is going straight to waste heat.

I guess It depends on what kind you use. The type I have don't get warm at all ,they don't get anywhere near as warm as a standard lightbulb. I don't know if it's due to the design, or the way the casing is built ,but you could holding your bare hand and you never know it had been plugged in.

The plastic top, sure. It's the base (metal bits) that gets scalding hot.

I'm surprised that they can get away with that. Could there have been an error in your measurement perhaps, especially regarding power factor?

Only possible explanation is that the switch on the lamp is terrible. And it sort of is. But I doubt to that extent.

 

[Sasqui]

If PFC which is expensive. The cheap LED lights are not, hence the substantial heat at the base. They're probably about 70% efficient so 30% of of the wattage consumed is going straight to waste heat.


The plastic top, sure. It's the base (metal bits) that gets scalding hot.

Just out of curiosity , I looked up the maximum theoretical lumens per watt for an LED itself. Assuming all light in the visible spectrum, It hovers somewhere around 390 lumens per watt. Our off the shelf LED bulbs are around 100 lumens/watt.

There is obviously a difference between the power inverter efficiency and the efficiency of the LED lights themselves... they both give off lost energy in heat (obviously)

 

[lexluthermiester]

Our local dollar store had a bunch and I ended up going back for a bunch more. 60w equivalent and they barely get warm. For $1, if they last a year, it's a good buy. CFL's put out much more heat.

 

[FordGT90Concept]

Mine have been running ~16 hours straight. The they are 90F at the tip and the hottest temp is 184F at the base (about dead center of the visible portion of the base). It's open air, no cover. It probably takes a long time to raise up to that temp but they will get there. CFLs get hot too, especially at the base.

They are TCP, 8.5w, 800 lumen. If memory serves, Kill-A-Watt detected 13-14w actual consumption.

 

[PLAfiller]

I haven't really checked the base to be honest. All my LED's are Philips, because they are almost the only one here with 1500 lumens per bulb. I like to have very clear light everywhere. I just can't stand a murky, muddy lighting for where I work/read/ play...whatever. Which reminds me, I need a desklamp. Probably from Ikea. I really like these guys

 

[qubit]

Only possible explanation is that the switch on the lamp is terrible. And it sort of is. But I doubt to that extent.

Maybe. My money is still on power factor correction.

 

[Sasqui]

Maybe. My money is still on power factor correction.

Personally, I doubt it... power factor is caused mostly by inductive reactance ...not much of that going on in a small power inverter.

 

[jboydgolfer]

The plastic top, sure. It's the base (metal bits) that gets scalding hot.

I was referring to the entire bulb ,anywhere on it at all. Unless it's cooling off from the time I get it unscrewed ,to where I touch it (which I guess is a possibility) but it's not warm when i hold (and handed it to my 9 y/o daughter). When I took them out recently, I was on a stepstool (because they were ceiling mounted),and my daughter was on the floor helping me.

 

[newtekie1]

People often confuse heat for temperature too. Just remember, just because something gets hot, doesn't mean it is actually producing a lot of heat. For the most part, the only area to disipate the heat generated on an LED light bulb is the base and screw. It doesn't take long for a small amount of heat generated to raise the temperature of that small surface area.

The bases get hot by design, they are heatsinks by design.

 

[eidairaman1]

I got 3 cabalara bulbs for 9-12 bux, way better than the cfls. CFLS are dinosaurs even compared to incadescent bulbs lol.

I have ballasts in the kitchen, really dont want to change them out, if they make leds in that surly I will get them

 

[Sasqui]

I got 3 cabalara bulbs for 9-12 bux, way better than the cfls. CFLS are dinosaurs even compared to incadescent bulbs lol.

I have ballasts in the kitchen, really dont want to change them out, if they make leds in that surly I will get them

I had two circ-line fluorescent fixtures in my kitchen, I gutted them of ballasts and hardware, and put in 3 standard sockets... tight fit but it worked. They now have both CFL's and LEDs in them to balance the light (warm and soft white). And soooo much cheaper to replace bulbs.

They make LED replacement bulbs for the long tube types HERES ONE ... it requires you to remove the ballast before using it

 

[erocker]

All the lights in my house are GE LED's. Of all the bulbs I have 3 that get hot at the base. Two are flood light replacements that go over the "kitchen bar", and the other is a 75w replacement in my work room. That one is a bit older than the rest (it's larger/longer too) and it gets really hot. From a couple videos n' such I've seen LED's seem to be cooled in a way that CPU's are cooled. There's a concentrated hot part that needs dissipation. The lower collar of the bulbs seem to be connected to that part and dissipate the heat. Anyways, 75w equivalent bulbs seem to be the point where they start getting warm to hot with this design.