Commuting - White LED selection for all you lighting experts

I have an old Performance 5-LED headlight. It's a fairly nice rechargeable design, but 2 of the LEDs are dead. I'm thinking about replacing them all with high-intensity white LEDs from Digikey: http://pdfcatalog.digikey.com/T063/1974-1975.pdf

If you scroll down to part # 365-1179-ND, you'll see that they have 1600 mcd white LEDs with a 50-degree viewing angle, in the ordinary 5mm round form, for $1.50 each. Are these a good deal? I would guess that the current LEDs have a 30-degree angle, and I'd like to increase it. Also, the forward voltage of the LEDs isn't specified by DigiKey... does anyone have a guess of what it might be? The current ones have a forward voltage of about 3.2V, and the batteries supply 4.8V.

One more thing: the current LEDs are encased in these silly little plastic lenses. Is there any good reason to reuse those? They seem to make the light a little more diffuse, but nothing else...

Actually... is there any reason I couldn't replace the 5 small LEDs with one big Luxeon 3W white LED? http://www.luxeonstar.com/item.php?id=381&link_str=&link_catg=&partno=LXHL-PW09

I could slap one of those on a PCB with a big resistor and have myself a brighter LED light, no?

Assuming those 5 LED's are .1W like most high powered 5mm white LED's, then you've only got a .5W power source to work with.

Assuming those 5 LED's are .1W like most high powered 5mm white LED's, then you've only got a .5W power source to work with.
Well, if I went with the Luxeon I'd remove the little power supply from the light, and just use a switch and a 5W resistor instead, I think.

1600 mcd isn't very bright. For comparison I know that the white leds in those three led cateyes are somewhere in the order of 6700 mcd. I'm using green leds with a 20 degree viewing angle that are 17000 mcd. They're pretty nice.

Have a look at www.superbrightleds.com for comparison in their discrete component section. They seem to be a little more retail oriented. I lust after their MR16 color changing LED bulb for freaking friends on Club night rides.

Check out this page.
http://autolumination.com/led.html
Good prices on 3-watt LED with heat sink platform and resistor pads.
Here is a good example of building your own light with one of them.
http://www.pilom.com/BicycleElectronics/LEDhead.htm

Thanks guys! I see that SuperBrightLEDs sells 5 mm white LEDs which do 18000 mcd and have only 120 mW dissipation. For only $1 too :) I think I'll get me some of those.

I don't know much about luminous intensity, but I'm told that a 60W incandescent is about 70 cd... so would 5 of those LEDs really put out as much as a 60W bulb viewed from straight ahead? If so, wow! That'd be freakin' awesome.

Thanks guys! I see that SuperBrightLEDs sells 5 mm white LEDs which do 18000 mcd and have only 120 mW dissipation. For only $1 too :) I think I'll get me some of those.

I don't know much about luminous intensity, but I'm told that a 60W incandescent is about 70 cd... so would 5 of those LEDs really put out as much as a 60W bulb viewed from straight ahead? If so, wow! That'd be freakin' awesome.

Yes. But the difference is, a 60W light bulb pours 70 cd in all directions, while the LEDs point in a single, narrower beam. With a reflector, that 60W incandescent would be brighter than the LEDs.

You can get white LEDs very cheap on eBay, too. Just watch out for people claiming to have 65000 mcd and 100,000mcd+ LEDs, these are false. 17000-18000mcd is generally the most you'll get out of a 5mm LED.

Check around before you wire up a Luxeons; I don't think you use a current limiting resistor with them. They need much better current regulation than that, so they have built into the emitter a current limiting IC that monitors both current and temperature. I think you just apply power and it deals with the limiting. Also realize that they must be attached to a heat sink or they will fry, particularly the 3W.

Yes. But the difference is, a 60W light bulb pours 70 cd in all directions, while the LEDs point in a single, narrower beam. With a reflector, that 60W incandescent would be brighter than the LEDs.

You can get white LEDs very cheap on eBay, too. Just watch out for people claiming to have 65000 mcd and 100,000mcd+ LEDs, these are false. 17000-18000mcd is generally the most you'll get out of a 5mm LED.
Wow... it's amazing how many folks are hawking LEDs from Hong Kong on eBay!!

Any reason not to replace the 0.1W 5 mm LEDs with 0.1W 10 mm LEDs? It seems like there are a lot of 10 mm LEDs for not much higher cost, and these are rated much higher by the eBay sellers. They would definitely fit inside this light... any reason not to go for that?

Thanks for all the help. I'm gonna order from eBay soon as I hear your opinions on the 10 mm's :D