# Lumen from big 75W light??



## FlashSpyJ (Jul 3, 2007)

I have found a big, but still portable light. I has a 12V acid battery, and a 75W bulb. 

My 2D ROP has a 7,2V Pelican bulb, 25w, if what I´m been told is right, I should get max 800 Light Lumen from the high ROP bulb?

So if thats true, how many Lumen should i expect from the 12V 75W light?
Reflector diam: 11cm (4,3").


----------



## LED61 (Jul 3, 2007)

FlashSpyJ said:


> I have found a big, but still portable light. I has a 12V acid battery, and a 75W bulb.
> 
> My 2D ROP has a 7,2V Pelican bulb, 25w, if what I´m been told is right, I should get max 800 Light Lumen from the high ROP bulb?
> 
> ...


 
This is just an educated guess, I´d venture say around 2100 bulb lumens and 65% of that out the torch ?


----------



## FlashSpyJ (Jul 3, 2007)

that would be quite good! perfect car light!

thanks alot! It must be somewhere around thoose numbers...


----------



## LED61 (Jul 3, 2007)

You´d also have to consider car lights are generally not overdriven, so that figure might still be in the high end of expectations, with 1900 lumens in the lower end. Again, just an educated guess.


----------



## FlashSpyJ (Jul 3, 2007)

guess I´ll never find out... thay where all out in every store! maybe not getting them back in, seems like they are very popoluar! its the second time they sell out of them....


----------



## LuxLuthor (Jul 3, 2007)

There's no way anyone can give any intelligent advice without knowing the exact make and model of bulb.


----------



## FlashSpyJ (Jul 3, 2007)

all info I can get, is that its a 12V 75W halogen bulb....


----------



## LED61 (Jul 4, 2007)

LuxLuthor said:


> There's no way anyone can give any intelligent advice without knowing the exact make and model of bulb.


 
And hence the terms "educated guess". Even if the exact model and make are not known the wattage of the bulb and the knowledge its for automotive use gives an approximate idea. I´m fairly sure I´ve seen a good deal of these bulbs rated at about 2000-2100 lumens.


----------



## mdocod (Jul 4, 2007)

Could easily be anywhere from 1000 to 2500 bulb lumens, just depends on how hard it is driven(life @~12V), fill gas, pressure, and philament design.


----------



## LuxLuthor (Jul 4, 2007)

LED61 said:


> And hence the terms "educated guess". Even if the exact model and make are not known the wattage of the bulb and the knowledge its for automotive use gives an approximate idea. I´m fairly sure I´ve seen a good deal of these bulbs rated at about 2000-2100 lumens.



The point is if it was a really cheap knock off brand with many construction flaws there could be a huge variation that could even range from several hundred lumen to many thousands. If he has the bulb and it has no identification other than 12V 75W, that is a pretty bad indictment of its lack of quality. We would like to give him more accurate information, but without a specific make/model, it is not possible.


----------



## LED61 (Jul 4, 2007)

mdocod said:


> Could easily be anywhere from 1000 to 2500 bulb lumens, just depends on how hard it is driven(life @~12V), fill gas, pressure, and philament design.


 
1000 bulb lumens ? An H1 12V 55W bulb is rated at about 1550 lumens and HB3´12V 60W go for about 1700 lumens. You think if the lights are as good and popular as they say they are a higher wattage would go that low in lumens ?


----------



## mdocod (Jul 6, 2007)

But the reality, is that automotive bulbs are designed for typical automotive applications, they *say* 12V bulbs because people *think* that cars are 12V systems. In reality, with the alternator running, 14V is more realistic. An H1 lamp that is "rated" 1550 lumen, probably only achieves that under ideal circumstances with low resistance to the lamp and the car running. Directly driven off a 12V battery, the bulb sees less voltage, and is therefor significantly dimmer.

The other issue at hand, is that wattage only plays 1 factor in brightness how hard the lamp is driven is a major factor. In reality, the 12V H1 lamp, probably achieves 1550 bulb lumens when driven at about 13.8V or so with about a 200 hour life. So if you turn off the key, and it only sees 12.5V, it drops to ~1100 lumens but jumps up to around 700 hours life. 

here's an example of a 50W halogen, 12V, that is only rated 600 lumens, but with 2000 hours life, (gently driven)
http://www.1000bulbs.com/product.php?product=676

here's an example of a 50W halogen, 12V, that is rated 1400 lumens, but only 50 hours life, (driven hard)
http://www.1000bulbs.com/product.php?product=1586

notice the massive variation in output at the same power consumption. When I was throwing some general numbers off the top of my head (anywhere from 1000 to 2500) I was not exaggerating the possible range, in fact, it would be very conceivable to have a 75W lamp that puts out even LESS than 1000 lumens.


----------

