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...
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!
Light bulb database - 1300+ bulbs compared... and counting
First the Advent candle and now this? You are my new hero.
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