# Light bulb database - 1300+ bulbs compared... and counting



## winny (Jan 6, 2007)

As I have no girlfriend or kids, I'm pretty much free to do whatever I want with my spare time and as one of my biggest interest is lamps and light, I have spent the last two months building a database of different bulbs. The reason for doing so is very simple. I have yet to this date seen any graph in any book or online for how the luminous efficiency changed with for example power. Philips and Osram have excellent graphs and functions for how the luminous flux, color temperature, current and power goes up and down with voltage FOR A PARTICULAR BULB (any bulb). That's good, but I want to see if it's better (more efficient) to use one 150 W bulb instead of three 60 W bulbs (it is by the way). 

The phenomenon is called impedance matching. Some people might get upset now, but bare with me on this one. Impedance matching is one of the most interesting things I have found in nature so far in my life. Have you ever thought about why it's easier to carry ten 10 kg stones up up a hill one by one rather than one 100 kg stone and then walk up and down nine times with just yourself although the amount of work done is the same? 
I have. 
This applies to light bulbs as well. That's the reason why a 12 V 60 W bulb is more efficient than a 230 V 60 W bulb, although they last just as long.

Anyone can make a list and compare things like that, but my interest (and time) doesn't stop there. I want to compare bulbs of all type, normal incandescent, halogen and IRC halogen and also reflector lamps. I find it most disturbing that lamp manufacturers (except some American ones for some reason) refuses to give luminous flux readings for their reflector lamps, although they would beat the Americans with good margins some times.  
In order to make a fair comparison, all bulbs must either have the same rated lifetime OR, much better, all be re-rated to a specific lifetime and then compared. Philips halogen OEM-guide had a most excellent graph for this purpose from which I extracted some re-rating formulas.
For reflector lamps, I reverse engineered (not much credits here, it was very easy) "LED center's" calculator (link here). Although far from perfect (it shows a reflector efficiency of 101% for 60 degree reflector lamps), it gives us a hint what to expect.

All Philips lamps I found interesting was entered manually as well as Sylvania whereas Osram and GE was semi-manual with some automation using OO Calc and Writer and Welch Allyn was fully automated using OO Calc. 
I intend to make a home page for this project where you can search for any bulb or just combinations (like you need 1000 lumen and have 15.6 V and you wounder what to use) and also add your own findings. More on that later.

As all bulbs are re-rated at 100 hours (could be anything, but 100 was even and good), I used my own unit, namely vinnberg for the lamps efficiency. It's nothing other than lm/W at 100 hours but if I would write that a 120 V 60 W bulb would have 20 lm/W @ 100 hours, I would get a bunch of e-mails asking how that could be and that I was wrong. The vast majority of those people will probably not give the vinnberg-unit any more thought and leave it there, hopefully.
I know you have to be dead and have gotten a Nobel prize or something similar to get a unit named after yourself but I gave Système international d'unités a call and they thought it was a such a good idea and let this one go.  

You have to think a bit outside the box to get the 100 hour-thing. Yes, some bulbs would have blacken if ran that hard but it could have been 1000 hours instead, the numbers would just be lower but the trends/results would be the same.

I plan to write more here later but I felt that this had to be planted soon so I get get some input/feedback first.


If we skip right along to the interesting part, luminous efficiency versus voltage and power, we can see some interesting things:






We can clearly see that running bulbs at say Mag 3D levels (~4 V), is a bad idea indeed. I would say that this is one of the main reasons why most incan flashlight people mod here are so bad before they are modded.
I also put some arrows here to point out some bulbs if interest. For example, the WA1185 is pretty good, but if you could use a higher voltage and another bulb, you could do the same more efficiency.
We can also see a strong trend here towards 12 V lamps. Don't think that 12 V is the answer for everything, but for most applications, it is!






In the power graph, we can clearly see that efficiency comes with power. That's why 1*150 W is more efficient than 3*60 W as I said in the start.






This one really speaks its clear language. Running at 260 mA (60 W, 230 V) is a bad idea indeed. The efficiency rises to twice the value with an increase of current by ten times up to about 5 ampere, then it decays. 


As I don't have any info about what Welch Allyn are halogen, IRC and so on, or not, they where excluded from my graphs from here on. Reflector lamps had to go here too, perhaps that was a bad call... :thinking: 






Not many incans here. 120 V lamps are generally more efficient, but I had some high powered 230 V ones here so you can't tell.





As this graph is mainly done from a few different series of bulbs, the trend is strong. Efficiency comes with power.






Your average 12 V bulb beats your average 120 or 230 V bulb. Some of the 230 V ones here are really high power as you can see in the next graph. Running at under 10 V seems like a bad idea.





Yes, again efficiency comes with power but decays some with that crazy 6 kW bulb.






Osram does sell Haloline IRC but they don't appear on their web page yet so I have to get back to you on that one. Still, you can't loose with IRC.





A slight trend here.


Any comment is welcome here!


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## winny (Jan 6, 2007)

Reserved for later...

I don't know why everyones does this, but I'll give it a shot.


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## Norm (Jan 6, 2007)

winny said:


> Have you ever thought about why it's easier to carry ten 10 kg stones up up a hill one by one rather than one 100 kg stone and then walk up and down nine times with just yourself although the amount of work done is the same?



Is the amount of work the same? Your first method involves 10 times the amount of travel, and by carrying one stone at a time you also increase the time over which the work is done.
Norm


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## winny (Jan 6, 2007)

Norm,

No. Perhaps I was unclear.

First method:
Take one stone, carry it up to the top, drop it off and head down.
Grab another one and repeat until you are out.

Second method:
Take all stones, or one big one, and carry it to the top. Drop it of there and head back. Go up and down nine more times without any stone. Call a chiropractor.

E=mgh so the amount of work is the same.


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## mrfrenzy (Jan 12, 2007)

Awesome Idea, can't wait to see a searchable database


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## carbine15 (Jan 12, 2007)

:bow:First the Advent candle and now this? You are my new hero.


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## brickbat (Jan 12, 2007)

winny said:


> That's the reason why a 12 V 60 W bulb is more efficient than a 230 V 60 W bulb, although they last just as long.



I don't see that your graphs back up this claim. I do see a strong correlation between lamp power and luminous efficacy, but the correlation between voltage is looser. In fact, my research shows that low voltage incandescent lamps operate at higher efficacy than high voltage lamps of the same wattage:


GE 50W 300V 1000 hours, 460 lumens, product code 16317
GE 50W 34V 1000 hours, 805 lumens, product code 10686
GE 50W 12V 1000 hours, 875 lumens, product code 16390

source data here:
http://www.gelighting.com/na/busine.../catalogs/downloads/2006_lampincandescent.pdf


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## 2xTrinity (Jan 13, 2007)

> I don't see that your graphs back up this claim. I do see a strong correlation between lamp power and luminous efficacy, but the correlation between voltage is looser. In fact, my research shows that low voltage incandescent lamps operate at higher efficacy than high voltage lamps of the same wattage


This actually is his point regarding mpedance matching. There is a general trend that incandescent light bulb increase in efficiency at greater power. However, I 'have noticed the same trend you are talking about, with lower voltage being more efficient at 50W.

Using Ohm's law, the power delivered to the light will be equal to Current squared times the resistance of the filament. A lower voltage source will require a higher current _and a lower resistance_ to produce the same output power. Lower resistance means a shorter filament, which means greater power _density_ along the length of the filament, when comparing a low voltage, short-filament bulb to a high voltage, longer-filament bulb.

As for impedance matching, the idea is that the power delivered to the load will be maximized when the impedance (in the case of a DC circuit, this is analogous to your battery internal resistance) is equal to the impedance of the load. This would usually be accomplished using an approrpaite transformer to deliver just the right voltage to a device in order to maximize the power output. I have wondered myself if using transformers to step down voltage for low-wattage light bulbs might be more efficient in the long run by being able to capitalize on this effect (though in my case, I'm already running CFLs for just about everything)


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## brickbat (Jan 13, 2007)

d'oh. brain fart. He did say exactly that...

I always thought it was because low voltage filaments, being made of thicker wire for a given wattage, aren't as fragile, and can be operated at higher temperature and still deliver the same operating lifetime.


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## 2xTrinity (Jan 13, 2007)

brickbat said:


> d'oh. brain fart. He did say exactly that...
> 
> I always thought it was because low voltage filaments, being made of thicker wire for a given wattage, aren't as fragile, and can be operated at higher temperature and still deliver the same operating lifetime.


I think both thicker and shorter filaments are used, so that's a good reason as well. Making the filament wider, or making it shorter would both reduce the resistance, and I believe both methods are implemented, and each have different effects. From what I understand though, the shorter filament length is why small track light fixtures are often designed to run off 12v, because they can have a tighter focus than 120v bulbs. 

Also, as the original poster said about this, there is a limit to how much you can lower the voltage to capitalize on these effects, giving the example of 4v incandescent flashlights generally being worse in lumens per watt. The reason for this is that the impedance mismatch is in the other direction -- if the internal resistance of the battery is greater than the resistance in the filament, less useful power will make it to the bulb as the current draw will strain the battery.


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## winny (Jan 14, 2007)

mrfrenzy,

Me too! I just need someone good with PHP or similar to make a web-interface for it.


carbine15,

Wow! Thanks a lot!  
Well, what can I say? I live for light.


brickbat,

I didn't point out any 12 V 60 W incans in the diagrams but you are, as you said, perfectly correct. Your thought is spot on! Free efficiency to the people!


2xTrinity,

Although I know you understood what I raved on about, I didn't mean to use impedance matching to squeeze out maximum power from any batteries, just trading voltage for current in order to optimize them for the filaments liking. That said, your example is a very good one for the things you can do with impedance matching! As you understand that, I think you would have a seriously good chance to score high in my "Are you an incan God?"-test, if I put it online. (So many things to do, so little time...)
When I worked as a janitor/housekeeper this summer, I teched my co-workers how impedance matching could be used. I manage to get one of them hooked on it. He was over 50 and had no academic education at all, still, he could after a week or so explain to anyone exactly why you shouldn't take too much dirt/gravel/whatever with your shovel, but rather take a bit less and work faster instead, or why you should use a rake for fir cones and a sweep brush for sand and not the other way round. Not just because it's obvious, but exactly what caused the phenomenon. Man was I happy contributing to the worlds understanding then. I even awarded him "Impedance matcher of the year" and he got a diploma and everything. I'll see if I can find some pictures of it. It was hilarious. God, what a summer it was...

About capitalizing the effect with a transformer, it's very very obvious. In my parents house, they have one room with 3*230 V, 50 W MR16 lamps and another with 4*12 V, 20 W MR16 and the 12 V-ers beat the crap out of the 230 V ones. Much brighter, cheaper lamps, and several times the lifetime. The transformer do hum, but that can be solved. Even with transformer losses, the 12 V ones pulls 33+% less power.



Now, I forgot to put the current-efficiency-diagram up, but I'll try to do it tomorrow. Right now I need to get some sleep. Studied for my re-exam until 3:30, then worked with our sound-and-light group fixing things until 11:30. Long days and no pay...


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## winny (Jan 14, 2007)

The forgotten current-efficiency curve:






This one really speaks its clear language. Running at 260 mA (60 W, 230 V) is a bad idea indeed. The efficiency rises to twice the value with an increase of current by ten times up to about 5 ampere, then it decays.


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## LuxLuthor (May 21, 2009)

Have to read this thread a few more times, but have already seen some interesting work that Winny did here.


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