Postby CleverNickName on Thu 24/Jul/08 2:53pm

swtchbckr wrote: so... i done write Cutter Electronics, asked 'em a little bit...
mark riley replied:
XRE are multi power devices i.e. can be run at 350mA(1.22 watt), 700ma(3watt), 1 amp(4.5 watt) or any number really dependent on your driver, however max rating is 1Amp
Q5 is is 94 Lumens per watt, R2 is 100 Lumens per watt


now i sorta need that deciphered...

basically, is that saying that if you're running 3 Q5's through an XRE, at 1 amp, the 1 amp, ie 4.5watts, is shared between the three LEDs making a total of 1.5 watts or 141 lumens per LED? or... and this where i think i'm wrong, does it pump 1 amp to each Q5, making 4.5 watts each, making 423 lumens per LED?? as in, a shit load of light, instead of just heaps.

Not quite, the product is a "Cree XRE". The "Q5", "R2" etc refer to binning or grading of an LED according to how much light it outputs.

the quoted 94 lumens/watt will be at peak efficiency, which decreases as you increase the current. In reality a Q5 will get about 220 Lumens at 1 amp

The current through any given LED depends on the driver and how the LEDs are wired
CleverNickName
Member for: 19 years 6 months

Postby swtchbckr on Thu 24/Jul/08 3:52pm

CleverNickName wrote: Not quite, the product is a "Cree XRE". The "Q5", "R2" etc refer to binning or grading of an LED according to how much light it outputs.

the quoted 94 lumens/watt will be at peak efficiency, which decreases as you increase the current. In reality a Q5 will get about 220 Lumens at 1 amp

The current through any given LED depends on the driver and how the LEDs are wired

Cool, but whats the story with regards running 3 of these Q5s? at 1 amp, are you getting the 220 lumens PER LED? or is that 1 amp split between the three? i cant seem to get me head round that bit...
in which case, if it is split, does that mean you'd get a total higher output from 3 than you would trying to blast out 1 amp through 1? (ie, current divided by 3, per LED, allowing better efficiency?)
sorry for being ignorant. i'm an ecogeospatial head, not an electronics head...
swtchbckr
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"Freakin' Mellonfarmer"
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Postby CleverNickName on Thu 24/Jul/08 4:28pm

swtchbckr wrote:
CleverNickName wrote: Not quite, the product is a "Cree XRE". The "Q5", "R2" etc refer to binning or grading of an LED according to how much light it outputs.

the quoted 94 lumens/watt will be at peak efficiency, which decreases as you increase the current. In reality a Q5 will get about 220 Lumens at 1 amp

The current through any given LED depends on the driver and how the LEDs are wired

Cool, but whats the story with regards running 3 of these Q5s? at 1 amp, are you getting the 220 lumens PER LED? or is that 1 amp split between the three? i cant seem to get me head round that bit...
in which case, if it is split, does that mean you'd get a total higher output from 3 than you would trying to blast out 1 amp through 1? (ie, current divided by 3, per LED, allowing better efficiency?)
sorry for being ignorant. i'm an ecogeospatial head, not an electronics head...

Have a look here: http://www.berkeleypoint.com/learning/p ... rcuit.html

If the LED's are wired in series (the top diagram) they all use 1 amp (about 220 lumens each or 660 total). Not all drivers will be able to drive 3 LEDs in series.

If they are wired in parallel, each LED will get about 0.33 amp (about 120 lumens each or 360 total)

If your choice is between 1 LED at 1 amp or 3 LEDs at .33 amp each, the latter will give you more light and run a lot cooler.
CleverNickName
Member for: 19 years 6 months

Postby plummet on Thu 24/Jul/08 11:23pm

what the driver does is sense if they are wired in series and ups the voltage as led's are added to retain the 1amp output.

so 1x 1amp led will run at 3.7 volts
2 in series 7.6 volts
3 in series 11.1 volts.

+ approx1.5 volts for the driver depending on brand.
plummet
Member for: 19 years 3 months

Postby Datsane on Fri 25/Jul/08 11:57am

plummet wrote: what the driver does is sense if they are wired in series and ups the voltage as led's are added to retain the 1amp output.

so 1x 1amp led will run at 3.7 volts
2 in series 7.6 volts
3 in series 11.1 volts.

+ approx1.5 volts for the driver depending on brand.
Thats true.
In series the current is constant its the voltage that veries and in parralalalallalaaaallll the voltage in the constant and the current veries.
Datsane
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Postby swtchbckr on Fri 25/Jul/08 12:42pm

Awesome...

So, from you 'ex spurts' experience, this XRE driver will be doing just that? at 1amp, 3 LEDs you're getting (theoretically) 660 lumens of light?

And thats comparable (or better?) than my current 35watt IRC halogen set up?
swtchbckr
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"Freakin' Mellonfarmer"
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Postby danose on Fri 25/Jul/08 12:48pm

swtchbckr wrote:
So, from you 'ex spurts' experience, this XRE driver will be doing just that? at 1amp, 3 LEDs you're getting (theoretically) 660 lumens of light?

And thats comparable (or better?) than my current 35watt IRC halogen set up?


nope - a 35W IRC halogen puts out more like 1000 lumens, so only 2/3 as bright (presuming the same beam width on both)

depending on your riding style you could possibly go narrower beam on the LED to get the same brightness at a given distance though
danose
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Postby znomit on Fri 25/Jul/08 1:12pm

danose wrote:
swtchbckr wrote:
So, from you 'ex spurts' experience, this XRE driver will be doing just that? at 1amp, 3 LEDs you're getting (theoretically) 660 lumens of light?

And thats comparable (or better?) than my current 35watt IRC halogen set up?


nope - a 35W IRC halogen puts out more like 1000 lumens, so only 2/3 as bright (presuming the same beam width on both)

depending on your riding style you could possibly go narrower beam on the LED to get the same brightness at a given distance though


Yeah, its not the lumens its where you point them. 660 lm is probably plenty if its coming from a couple of spots and one wide. If you're not happy another light on the helmet helps.

Halogens are variable in quality too. Some are very good and some shite.
This link gets bandied about a lot for halogen lumens. I know my vespa has a crappy 35W halogen and its about the same as my old 500lm led setup... and my 700lm is about the same as a 50W DIY halogen of a local guy.
http://nordicgroup.us/s78/wattslumens.html
znomit
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Member for: 14 years 2 months

Postby danose on Fri 25/Jul/08 1:23pm

znomit wrote:Yeah, its not the lumens its where you point them. 660 lm is probably plenty if its coming from a couple of spots and one wide.


that's the big win with led - running 3 or 4 emitters you can mix/match optics - wheras with halogen I always wanted a wider beam on slower/twisty stuff then a real pencil beam on descents

wonder if eventually we'll see adjustable optics (like my old petzl duo climbing headlamp - actually really useful)

Halogens are variable in quality too. Some are very good and some shite.


absolutely - 1000lm is right for a top quality Osram 35W IRC, brand new (cos output drops with age) AND over-volted slightly
danose
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Postby swtchbckr on Fri 25/Jul/08 3:40pm

i like the sound of the 3 Q5s with a 6 degree spread.

sounds like the 660 lumens will be similar to a 20W IRC halo, which i've survived with occasionally. the 35W IRC i run is getting on in age, so wont be full power any more... cool. next time i've got a spare hundy i'm gonna get me some o' these Cutter's Crees...
swtchbckr
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Postby plummet on Fri 25/Jul/08 4:09pm

i rate my 2 xre q5's mounted individually for better light spread better than my 35w halogen. i'm using 1 x 8.5 and 1 x 10.5 lenses.

however if your going to mount 3 leds in one housing and point them all in the same spot they wont through as gooder light spread and therefore be less efficient. probably similar to my 2 emitters.
plummet
Member for: 19 years 3 months

Postby znomit on Fri 25/Jul/08 4:59pm

danose wrote:
that's the big win with led - running 3 or 4 emitters you can mix/match optics - wheras with halogen I always wanted a wider beam on slower/twisty stuff then a real pencil beam on descents

wonder if eventually we'll see adjustable optics (like my old petzl duo climbing headlamp - actually really useful)


Adjustable led optics here
http://www.cutter.com.au/proddetail.php?prod=cut188

I built a quad led that had two pointing forward and two angled side/down a little. Worked ok, shouldn't have angled them down because I had too much light in close. A switch unbalanced the 2 led strings and put less current into the wide leds and more up front.
http://www.candlepowerforums.com/vb/showthread.php?t=174539

My helmet light has individually switched 25 and 6degree beams.
http://www.candlepowerforums.com/vb/showpost.php?p=2463166&postcount=24
znomit
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Member for: 14 years 2 months

Postby Datsane on Sat 26/Jul/08 1:08pm

danose wrote:
swtchbckr wrote:
So, from you 'ex spurts' experience, this XRE driver will be doing just that? at 1amp, 3 LEDs you're getting (theoretically) 660 lumens of light?

And thats comparable (or better?) than my current 35watt IRC halogen set up?


nope - a 35W IRC halogen puts out more like 1000 lumens, so only 2/3 as bright (presuming the same beam width on both)

depending on your riding style you could possibly go narrower beam on the LED to get the same brightness at a given distance though
Halogen will be really bright for the first 5minutes of the battery life then drop off quickly after that.
With LED's you could run enough emitters to produce the same amount of lumens and still have better burn time and less weight.
Datsane
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Member for: 18 years 2 months

Postby plummet on Sat 26/Jul/08 10:38pm

ok i decided to time my battery to see how long before in goes flat.

i've 2 1 amp xre q5's wired in series and a buck puck driver i'm using a li-ion battery 11.1 v 2.2 amp hour

my maths tells me i should get around 3 hours out of these lights on full ra.

any way i'm running a dimmer and have backed off the dimmer until i notice a drop in light. I then turn it up slightly so its as bright as full power (well it looks the same).

my lights are still going 7 hours later.....

wholy long run time batman...

either my maths are stuffed up or the LED's burn almost as bright on half power!.
plummet
Member for: 19 years 3 months

Postby Slim on Sun 27/Jul/08 8:50am

plummet wrote: ok i decided to time my battery to see how long before in goes flat.

i've 2 1 amp xre q5's wired in series and a buck puck driver i'm using a li-ion battery 11.1 v 2.2 amp hour

my maths tells me i should get around 3 hours out of these lights on full ra.

any way i'm running a dimmer and have backed off the dimmer until i notice a drop in light. I then turn it up slightly so its as bright as full power (well it looks the same).

my lights are still going 7 hours later.....

wholy long run time batman...

either my maths are stuffed up or the LED's burn almost as bright on half power!.



I am running 3 leds on a similar setup and get 5.5 hours on full noise.
Slim
Member for: 19 years 0 months

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