# Housing for 7UP XPG?



## sergio_pt (Jan 29, 2007)

Anyone knows where to get a round housing to fit this Cree 7up XPG on 40mm MCPCB plus the  Khatod PL1211xx 7 up series optics??

If this PCB and optics exist, they must be made to fit somewhere! So I assume some company manufactures this. Anyone has a clue? 
A custom machining or CNC would be OK too. 
If someone is interested in making me one please PM or reply.

7 XPG would give a pretty nice light with 3000+ Lumen output!  :thumbsup:


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## thwang-01 (Jul 5, 2008)

hi 
have a word with troutie or yetibetty


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## troutie-mtb (Sep 20, 2007)

Yetibetty has one in the pipeline with pics on here 

I have 4 of the beasts stuck somewhere in the UK postal system 
so should have something soon 

2 days from Australia to UK 5 days so far in the uk and I have not seen them yet 
Bastids :madmax:


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## sergio_pt (Jan 29, 2007)

troutie-mtb said:


> Yetibetty has one in the pipeline with pics on here
> 
> I have 4 of the beasts stuck somewhere in the UK postal system
> so should have something soon
> ...


yep I've contacted him.

Are you planing a round housing too troutie?

A Lumen liberator with 7 or 8 XPG S2 LED's would be a good idea. At least for me


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## znomit (Dec 27, 2007)

Try nightlightning too, I think they used to do a 50mm before switching to MR11 36mm.


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## yetibetty (Dec 24, 2007)

sergio_pt,

I've sent you a reply


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## troutie-mtb (Sep 20, 2007)

sergio_pt said:


> yep I've contacted him.
> 
> Are you planing a round housing too troutie?
> 
> A Lumen liberator with 7 or 8 XPG S2 LED's would be a good idea. At least for me


I will certainly by doing something when they arrive 40 mm dia sounds a nice size
7 xpgs is on the limit for the Maxflex

be interesting to see what the 6 degree optic is like


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## sergio_pt (Jan 29, 2007)

znomit said:


> Try nightlightning too, I think they used to do a 50mm before switching to MR11 36mm.


thanks for the link!

Lets see who come up with the best round design!



yetibetty said:


> sergio_pt,
> 
> I've sent you a reply


cool thanks :thumbsup:



troutie-mtb said:


> I will certainly by doing something when they arrive 40 mm dia sounds a nice size
> 7 xpgs is on the limit for the Maxflex
> 
> be interesting to see what the 6 degree optic is like


Yep looks like 7 is the optimum number of XPGs to go with the maxflex. 
I'm interested to know how your design will look like.

6º optics is too narrow maybe? I'll bet in the 25º

have they arrived yet?


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## peteredm (Oct 9, 2009)

*xp-g driver and batteries for 7up?*

What batteries and driver would you use to power the 7up xp-g from cutter.com.au for a decent run time.

the 7up is wired up in series too so could you use the driver to output a lower amp rating for a longer run time.

Think I'm going to run the 3up for my first diy project but he 7 up would be meaty, what do you reckon to the optics for the 7 up also..

Thanks

Pete


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## sergio_pt (Jan 29, 2007)

peteredm said:


> What batteries and driver would you use to power the 7up xp-g from cutter.com.au for a decent run time.
> 
> the 7up is wired up in series too so could you use the driver to output a lower amp rating for a longer run time.
> 
> ...


One of the best options to drive 7XPG's will be the Maxflex driver, you can order from that page too (available Tuesday).

2P(3S) of 18650 will give you 2-3hr on maximum.

Optics, there is none designed specifically for the XPG yet. 
You can use the XPE XPC optics but these will give a wider beam as other guys have said


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## HEY HEY ITS HENDO (Feb 23, 2008)

> 2P(3S) of 18650 will give you 2-3hr on* maximum*.


sergio_pt, what would be the input current using this configuration??


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## sergio_pt (Jan 29, 2007)

By ledcalc 
Desired LED Current: 1000mA 
LED Forward Voltage: 23.1V <<< 7 LEDs times 3.3 volts per LED
Battery Input Voltage: 14.8V 
Battery Capacity: 4800mAh 
Converter Efficiency: 80%

Runtime: 2hr 27min

The theoretically calc is correct but I said it was 2P(3S)
Small mistake. I used 14.8V as 2x(4x18650) cells in that calc.

For the cell pack I have 2x(3x18650) for 11.1V will be about 2hr runtime.


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## HEY HEY ITS HENDO (Feb 23, 2008)

ahh i was thinking the Desired LED Current:1200ma
(maxflex on full )
anyway the maxflex would have an easier life on the 4 cell voltage
remember voltage sags when you whack it on full 
and what a pity the input voltage is limited to only 20v..
otherwise a 5s battery pack could have been used :madman:


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## HuffyPuffy (Jun 9, 2008)

A maglight head is 48mm inside and about 19mm deep. With some trimming it could work if the stack height is not too much.


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## yetibetty (Dec 24, 2007)

HEY HEY ITS HENDO said:


> ahh i was thinking the Desired LED Current:1200ma
> (maxflex on full )
> anyway the maxflex would have an easier life on the 4 cell voltage
> remember voltage sags when you whack it on full
> ...


That's ballsed up my plan, I was going to use my 5s (18.5v nominal 21v straight off charger) as that would be easy to boost to 23v.
I Never botherd to check and asumed it would have the same 25v max input as the bFlex


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## troutie-mtb (Sep 20, 2007)

yetibetty said:


> That's ballsed up my plan, I was going to use my 5s (18.5v nominal 21v straight off charger) as that would be easy to boost to 23v.
> I Never botherd to check and asumed it would have the same 25v max input as the bFlex


I asked George about this a while ago here is his answer.

Chris wrote: 
Hi George .

Would a Maxflex be ok for the 7 up XPG board if the vf is as stated 3.3 v @ 1000ma then that would be 23.1 v 
are we flying close to the wind what are your views apart from we are mad

Cheers Chris

Chris,
the 23.1V is getting close to the open circuit protection voltage. It's not like it will blow up or anything, just that once it gets to the OC voltage the driver will no longer be in regulation - since it will switch over to voltage regulation (the OC voltage limit) and so output current would drop. i.e. if you hooked 10 LEDs the driver would still limit to ~24V so each LED would only get 2.4V - very dim.

So, we're not talking any real 'limit' in terms of power etc. The key is you can push all the way to 24V at 1A, but if the LED total Vf is above that then the driver can't push the voltage any higher and the output current will drop. All very safe.

The main thing is to keep input current down since that will provide the best efficiency - and that means higher battery voltage. Of course the battery voltage can't be so high as to prevent dimming. So, if we say 7 LEDs and 1A at 3.3V each, then 23.1V is the max - all good, no when dimmed to say L1 (50mA) we have maybe 2.6V per LED, so now we have 2.6 x 7 = ~18V. So, we need a battery that is less than 18V but as close to that as possible. This means 4 li-ion cells.

Remember to read http://www.taskled.com/leds/max4_thermal_guide.pdf and you'll see my tests were close to what you are planning. The first test is close to your setup, I had 21V at 1A from 14V input. Basically you need a good heatsink path to the gold area of the PCB. If you really push the envelope, then a 2nd heatsink path to the inductor will let you easily handle things.

cheers,
george.


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## yetibetty (Dec 24, 2007)

Thanks Troutie,
Hmmmmm yet another battery pack to build, I have a few 5s packs for running my quads with bFex's.
Could use my RC balance charger and programe it to stop charging at 18v(end voltage setting)

Instead of that maybe break a trace on the LED board, master & slave two bFlex's, run four LEDs from one & three from the other. that will keep the 25v max input so batteries will be OK.

That's if I ever get my LEDs They are stuck in the UK postal system!!!


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## sergio_pt (Jan 29, 2007)

Is it possible that the XPG's in the array are "requesting" more than 3.3Volt to be driven at maximum brightness? If all LED's need more 3.4Volt for this then maxflex cant keep up!

I think a driver with superior maximum output voltage would be great for the 7UP app, just to keep a safe interval.

Is it hard to tweak the maximum output voltage of maxflex?


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## yetibetty (Dec 24, 2007)

Thinking about it full power won't be required very often in the average ride and can be saved as a "boost mode". It's going to be seven XPG's remember.

90% of the time 700ma should be fine, have a lower vf and run cooler too.


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## HEY HEY ITS HENDO (Feb 23, 2008)

Hyperboost anyone?? . ...http://www.taskled.com/hboost.html

http://www.candlepowerforums.com/vb/showthread.php?p=3091392#post3091392


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## yetibetty (Dec 24, 2007)

HEY HEY ITS HENDO said:


> Hyperboost anyone?? . ...http://www.taskled.com/hboost.html
> 
> http://www.candlepowerforums.com/vb/showthread.php?p=3091392#post3091392


Hendo,
looked into that but it is huge and there are no Flex features, low battery warning etc.
We don't ask for much do we


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## sergio_pt (Jan 29, 2007)

yetibetty said:


> Thinking about it full power won't be required very often in the average ride and can be saved as a "boost mode". It's going to be seven XPG's remember.
> 
> 90% of the time 700ma should be fine, have a lower vf and run cooler too.


Maybe It'll be enough, but building this ultimate light and knowing that it could deliver even more light would leave me a bit disappointed and with a taste of mission not accomplished. And I always want more light!  yeah 7XPG! I hope they meet my expectations at least.

what are the dimensions of Hyperboost? Diameter, height?


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## BlackDawn (Nov 19, 2007)

I'm going to use nflex + 7 cell, should work if you don't mind being squre


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## ifor (Apr 15, 2008)

I had forgoten the nflex went up to 30V on the input well spoted should work very nicely. I would advice heatsinking it, a few slivers of alu can get the inductor, cap and switcher chip to the same height to mount to a flat case. 

Pitty George looks to of discontinued them. I think I have two installed in rearly used lights I may have to liberate one but I will see what happens with a maxflex first once the 7up arives.....

Ifor


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## BlackDawn (Nov 19, 2007)

my bad, none left :-( 
ifor you wanna sell me one of yours?


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## ifor (Apr 15, 2008)

No Thanks like i said they are both in lights so I would rether leave them. I hope a Maxflex is going to be good actualy, should be on the 'typical' figures. The problem is we don't yet know what sort of variation there is not enough reports in.


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## yetibetty (Dec 24, 2007)

Postman came at last 

39mm of fun.


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## sergio_pt (Jan 29, 2007)

tiny thingy LED's! Will that reaaly give +2500 lumen? Light it up!


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## yetibetty (Dec 24, 2007)

sergio_pt said:


> tiny thingy LED's! Will that reaaly give +2500 lumen? Light it up!


I never believe what I read when it comes to lumens, no one kows what a lumen looks like anyway.
But it should be nice and bright.

Shold also add that Cutter were very fast in getting them to the UK & the delay was the UK postal service( or lack of )


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## HEY HEY ITS HENDO (Feb 23, 2008)

jeez its true.....

0 (production ended)........nFlex Driver boards With New UI-uni firmware

.......tiny thingy LED's! yes they are unbelievably minute!!


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## Whitedog1 (Feb 3, 2009)

hey,

will the 7up pcb fit into the DX Bike light housing? 
The plan could be to make a new heatsink that fits into the DX housing ond to put the 7up on that heatsinkt......... if it fits??  

I think the sizes seem to be very similar - but i don't have one to measure! :madman: 


Just an idea


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## ortelius (Dec 6, 2007)

Even if the pcb fits, which driver are you planing to squeeze in there then to run those 7 leds?


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## Whitedog1 (Feb 3, 2009)

The 7up optic is not so high as the stock dx reflector is, so it should be possible to gain a little more space in there to fit a driver!

Perhaps the Maxflex5 will do the best job


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## HuffyPuffy (Jun 9, 2008)

Does anyone know the stack height of the 7up optic and LED board?


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## sergio_pt (Jan 29, 2007)

http://www.khatod.com/Documenti/pl121106_cre_technical_detail.pdf


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## Cat-man-do (May 16, 2004)

Whitedog1 said:


> hey,
> 
> will the 7up pcb fit into the DX Bike light housing?
> The plan could be to make a new heatsink that fits into the DX housing ond to put the 7up on that heatsinkt......... if it fits??
> ...


...a very good idea, providing you can design a heat sink that can get rid of the heat of 7 leds. I think I would be looking more into the Iblast designed housings as they look to be better prepared to dissipate heat. The 7-up boards look nice but trying to dissipate all that heat ( in a cluster formation ) is going to be the real trick.


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## chrissa (Dec 17, 2006)

The inside diameter of a DX light body is about 36mm. The glass lens is about 39mm and is sandwiched between the light body and screw-on front bezel.


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## troutie-mtb (Sep 20, 2007)

HuffyPuffy said:


> Does anyone know the stack height of the 7up optic and LED board?


Yes it is 13 mm and 39 mm diameter 
but on the stack height it will need a front glass if using the 6 degree as there are the holes down the middle of each lens which would fill with crap .

No way is the DX bastid any good for this board and optic . though some one may prove me wrong .

Yettibetty has the right idea as there is a fair amount of heat from this puppy .
another thing is you cant have a centre hole for the wires and it is the middle led that is going to suffer the most .


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## Whitedog1 (Feb 3, 2009)

chrissa said:


> The inside diameter of a DX light body is about 36mm. The glass lens is about 39mm and is sandwiched between the light body and screw-on front bezel.


I would say this kills my project 

But i measured the diameter of my Romisen RC-T5 - the 7up should fit in there :idea: 
just need to get rid of the driver problem...:eekster:


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## yetibetty (Dec 24, 2007)

Troutie, you can put two tiny wire holes in the housing either side of the center LED and use the PCB's center wiring holes and pads. Its a well thought out PCB with provision for center or side wiring also the wires do not get in the way of the optic.............


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## yetibetty (Dec 24, 2007)

.............. and as they say in cookery programs "here's one I made earlier" It was a bit of a challenge for my Taig micro lathe and a giant challenge for me. 

Oh and if my neighbours just happen to read this.....sorry about all the noise(not)

Got to get it to Sergio now with no post!!!! (and do it all over again if I want one for myself).


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## OldMTBfreak (Apr 8, 2006)

OMG YB, that's a beauty! I think the 7up is going to be shitz.


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## znomit (Dec 27, 2007)

yetibetty said:


> Troutie, you can put two tiny wire holes in the housing either side of the center LED and use the PCB's center wiring holes and pads. Its a well thought out PCB with provision for center or side wiring also the wires do not get in the way of the optic.............


Thats good thinking.
The pads next to the leds... what are they for?

More importantly, do I need a 1400lm dyno light...


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## yetibetty (Dec 24, 2007)

Thanks Mr Old, the thing I like is that is isn't really that much bigger than a quad from last year(XRE) and with a short test from the mains with a 24v transformer it gets no hotter due to the slightly larger housing and better efficiency.

Obviously this may change with a red hot maxflex inside too. But I can't get one due to the UK postal strikes.

Pic next to a quad for size comparison.


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## neal_b (Apr 4, 2007)

Nice looking light there Yeti. How are you mounting them up?


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## yetibetty (Dec 24, 2007)

neal_b said:


> Nice looking light there Yeti. How are you mounting them up?


I use the Exposure quick release(bar mount) made by USE.


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## troutie-mtb (Sep 20, 2007)

Wow Yetti that is very good well done You must be Stoked

I can get a maxflex in the post to you monday if you need on in a hurry 
or is your stuck in the 30 000 000 delayed letters in our system

I have not had a chance to play with mine with the crazy demand for the LL So gave one to the guy who does my cnc machining and just said do something with this and will wait and see what appears .

This is where the the other one is the IKEA lights in my officw have died so it is now lit with it










It has got about 30 hours on it now running @ 350 ma with the odd blast at 500 ma when doing fiddly stuff works a treat


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## yetibetty (Dec 24, 2007)

Thanks for the offer trout but I'm not in a rush. Once I get this housing sent off to Sergio I'll have to start over and do another housing for myself and I am not fast.

Very pleased with how it turned out though.


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## WeLight (Aug 12, 2007)

znomit said:


> Thats good thinking.
> The pads next to the leds... what are they for?
> 
> More importantly, do I need a 1400lm dyno light...


Thermal test points for checking tj's


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## 02Slayer (Mar 5, 2004)

Nice YB! Maybe my Tank housings will come in handy after all.


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## Rich_SC (Oct 10, 2009)

yeti: how do intend to waterproof the front optic? I was wondering how hard it would be to have an end piece milled so that it threads on with a glass front (ala the magicshine housing).


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## sergio_pt (Jan 29, 2007)

yetibetty said:


> .............. and as they say in cookery programs "here's one I made earlier" It was a bit of a challenge for my Taig micro lathe and a giant challenge for me.
> 
> Oh and if my neighbours just happen to read this.....sorry about all the noise(not)
> 
> Got to get it to Sergio now with no post!!!! (and do it all over again if I want one for myself).


And you completed the challenge very well, thanks for making it! :thumbsup:  
Cant wait to play with it. 

Some more pictures, from round block to the micro lathe to housing.


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## emu26 (Jun 23, 2008)

WOW Yetti that looks so neat.

Nice work


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## ocean breathes salty (Oct 1, 2006)

emu26 said:


> WOW Yetti that looks so neat.
> 
> Nice work


+1

I love the little lathe as well. I might even have some space to store something that size.


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## emu26 (Jun 23, 2008)

My thoughts exactly Salty, and lookey here, we can actually get that one locally.

Mind you the US supplier sells it with the motor for cheaper. I wonder what the postage on that would be?


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## yetibetty (Dec 24, 2007)

So you like the little Taig then? It was actually El34 who told me about them and I love the thing, It takes up no room and you can mod it to your own spec.

It's quite basic though but I like the old fashion engineering thing.
Loads of stuff here: http://www.cartertools.com/ and this is the UK supplier: http://www.peatol.com/

This is mine that Iv'e adapted over the past 3 months & what it looks like after a hard days work.


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## kwarwick (Jun 12, 2004)

*Possible flashlight host*

I was looking at my flashaholics collection of Chinese flashlights and discovered that my long ignored Romisen RC-T5 seems to have some potential. The pill that the existing 4 Cree XR-Es are attached to seems to be the right diameter. The reflector is approximately 19mm deep, so some adjustments would be needed to accommodate the Carlco 7 up optics, but perhaps this is an opportunity to slide in some additional heat-sinking in the form of a copper disc?

So the question is could this be a viable host for 7 XPGs running anywhere near full tilt or would it be a meltdown waiting to happen?


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## Whitedog1 (Feb 3, 2009)

hey kwarwick

i have also measured the RC-T5!  
but i measured the inner diameter of the housing and it is 39mm

you measured the outer diameter of the heatsink witch includes the threads :nono: 

I would say the 7up XP-G board will probably fit - maybe you will habe to grind down the outer side of the board a little bit to fit inside the housing! :eekster: 

Either way i think a new heatsink should be made which is optimised to fit an appropriate driver and ensures that the stack hight with the optic is near the front lens! (just m2c)


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## troutie-mtb (Sep 20, 2007)

kwarwick said:


> I was looking at my flashaholics collection of Chinese flashlights and discovered that my long ignored Romisen RC-T5 seems to have some potential. The pill that the existing 4 Cree XR-Es are attached to seems to be the right diameter. The reflector is approximately 19mm deep, so some adjustments would be needed to accommodate the Carlco 7 up optics, but perhaps this is an opportunity to slide in some additional heat-sinking in the form of a copper disc?
> 
> So the question is could this be a viable host for 7 XPGs running anywhere near full tilt or would it be a meltdown waiting to happen?


From my early messing with a 7up at full whack I would bet on meltdown unless you live in the arctic circle .or cycle very fast


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## sergio_pt (Jan 29, 2007)

And I received the 7UP housing from yetibetty today! Its a nice work of art. I hope it deals well with the heat. 
I was thinking about placing the XP-G's directly on the aluminium housing to improve heat transfer and not using the Multiple Chip PCB. Might be a difficult precision work though. What do you think??


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## odtexas (Oct 2, 2008)

Put that idea in the same category as you building your own battery holder.


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## Rich_SC (Oct 10, 2009)

Yeah...the board-LED-optics are a pretty sweet package. And you have a housing custom made for it. Rock it!


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## BlackDawn (Nov 19, 2007)

I was thinking the same thing, and it just doesn't comply with the "KISS" principle so I say use the mcpcb.
I would like to see cutter move to a copper base.


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## sergio_pt (Jan 29, 2007)

Yes its simpler to use the MCPCB, but how good is a PCB transferring heat?.


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## BlackDawn (Nov 19, 2007)

IMHO it's all up to the thermal paste, in the end it's alu-gap-alu, as long as you fill the gap properly with a good thermal paste it should be almost the same as laying the LEDs on the body.


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## WeLight (Aug 12, 2007)

fyi, the mcpcb's we use are typically <= 2 deg C/w in thermal resistance


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## sergio_pt (Jan 29, 2007)

WeLight said:


> fyi, the mcpcb's we use are typically <= 2 deg C/w in thermal resistance


Thanks for the info WeLight :thumbsup:

BTW what about a special promotion on 7UP MCPCB + Optics combo the for the flashaholics here?


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## BlackDawn (Nov 19, 2007)

:thumbsup: 
and XPG25SQ + PL1151


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## znomit (Dec 27, 2007)

sergio_pt said:


> Yes its simpler to use the MCPCB, but how good is a PCB transferring heat?.


A traditional PCB? Not so good.
Ask Lupine.


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## Bazillus (Dec 1, 2009)

Hi Yetibetty,

did you measure the case temperature when you drive all 7 leds with a current of 1A? Is it possible to drive the leds in your case continuously at 1A? And what about the temperature during a ride?

I started to build a bike light with 3 x XR-E Q5 at 1A (which means approx. 12W power dissipation) mounted on a SK572-50mm heatsink from Fischer Elektronik (http://www.fischerelektronik.de/index.php?id=114&L=0&[email protected]@[email protected]_) and this already gets quite warm (around 50°C).

Best regards from Austria

Michael


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## yetibetty (Dec 24, 2007)

Bazillus, I have tested it at 1A and you can fry eggs on it when not on the move, so just turn the power down when stationery. Good news is that it cools realy fast due to all the fins and only a small amount of air flow is required to keep it cool(cooler!).

When riding in the cooler night air at 1A it gets to around 50c and I use the drivers thermal management to keep things safe.


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## Jim Z in VT (Sep 9, 2007)

YB, is it difficult to clean the eggs out of the fins after they're cooked?  

I wonder if an anodizing shop could do a Teflon coating.

OK, I will shut up and go away now....I think I have one more of those yummy porters in the fridge.....

JZ


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## yetibetty (Dec 24, 2007)

Jim Z in VT said:


> YB, is it difficult to clean the eggs out of the fins after they're cooked?
> 
> I wonder if an anodizing shop could do a Teflon coating.
> 
> ...


Eggs are not a problem but the bacon & beans stick like crazy.

Enjoy your beer


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## troutie-mtb (Sep 20, 2007)

same with my case gets hot as hell if still on max and just luke warm when moving 

tested it walking the dog and it was a great hand warmer too 

I find wrapping the bacon around works nicely but the eggs are a problem


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## OldMTBfreak (Apr 8, 2006)

uuuum bacon!


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## yetibetty (Dec 24, 2007)

Things stick a lot more since I've done some tweeks!!!


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## Jim Z in VT (Sep 9, 2007)

troutie-mtb said:


> I find wrapping the bacon around works nicely


Now you not only have some of the best looking lights around, but the best _smelling_ lights as well!


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## God_Speed (Oct 5, 2007)

sergio_pt said:


> By ledcalc
> Desired LED Current: 1000mA
> LED Forward Voltage: 23.1V <<< 7 LEDs times 3.3 volts per LED
> Battery Input Voltage: 14.8V
> ...


I just cant seem to get it right with the calc for what I wanna do. Use Led pro 2.12 calc.

Id like to use an extra Hope 7,4v 5200mAh (4cell) to drive XP-G leds. If I run them as low as 500mAh can I get the 7led version to run with my battery? Plan on using MaxFlex5 driver.


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## sergio_pt (Jan 29, 2007)

God_Speed said:


> I just cant seem to get it right with the calc for what I wanna do. Use Led pro 2.12 calc.
> 
> Id like to use an extra Hope 7,4v 5200mAh (4cell) to drive XP-G leds. If I run them as low as 500mAh can I get the 7led version to run with my battery? Plan on using MaxFlex5 driver.


It'll work fine. My new LED Runtime Calculator V1.1 indicates 3hr runtime. (XPG at 500mA needs 3.1v)

The rest of the site is not complete yet..


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## yetibetty (Dec 24, 2007)

God_Speed said:


> I just cant seem to get it right with the calc for what I wanna do. Use Led pro 2.12 calc.
> 
> Id like to use an extra Hope 7,4v 5200mAh (4cell) to drive XP-G leds. If I run them as low as 500mAh can I get the 7led version to run with my battery? Plan on using MaxFlex5 driver.


Even at 500 ma the LED's vf is more than 20 v so I think it would be too much work for the Maxflex and it would probably over heat trying to boost 7.4v up to 20v.

Somehow Lupine manage to run 7 LEDs of 7.4v though.


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## troutie-mtb (Sep 20, 2007)

I have posted this reply from taskled before 
but he explains it better than I could

Hi Chris,
6 XPE is more like 6 x 3.5 = 21V ?? Yes, 14.4V would be the minimum I'd recommend to try and keep input current low and efficiency high. I'd NOT recommend 11.1V, that will mean >2A at the input AND because of the large delta between input voltage and output voltage, efficiency will be <<90%. That would be >2W being dissipated in the switcher IC - too much... Forget 7.2V!

No problems for bFlex - it really doesn't care whether you have 3 LEDs at 1A or 2 parallel strings of 3 LEDs at 1A - it is the same load...

Truth be told, I "DON'T" like boost converters and only designed/built maxFlex due to customer pressure. Buck converters like bFlex are so much easier to design with and have much better thermal characteristics ->

Boost converters and batteries are a lose/lose combo. While the battery is fresh, the efficiency is best (since input voltage is higher). As the battery drains, the input voltage drops, efficiency gets worst, heat losses get higher, input current increases. Everything is in the bad direction.

Buck converters and batteries are nice. As the battery voltage drops, the input current increases, but never more than the output current, BUT as the input voltage lowers, the efficiency of the driver increases (higher efficiency with small input/out voltage delta). As the input voltage reaches the output voltage (if that is the LED/battery combo), then input current will then drop as it goes out of regulation - never has input current gone greater than output current. So, you can see a buck with batteries offers very nice operating characteristics.

So, in summary, IF you can configure your LED/Battery needs to be able to use a buck converter, you will miles ahead of the boost crowd...

I've had lots of folk destroy maxflex drivers because of overheating due to poor choice of LED load, LED current and input battery voltage and poor heatsinking. I've NEVER had a bFlex fail due to overheating (and no one heatsinks that driver)...

cheers,
george.


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## God_Speed (Oct 5, 2007)

yetibetty said:


> Even at 500 ma the LED's vf is more than 20 v so I think it would be too much work for the Maxflex and it would probably over heat trying to boost 7.4v up to 20v.
> 
> Somehow Lupine manage to run 7 LEDs of 7.4v though.


So the biggest problem with the big differance between 7,4v and ~22v the leds will need is the heat it will generate in the MaxFlex driver?

If Lupine are able to handle that heat it should not be impossible? May be more controlable in the rather big modifyed MagLite hosing (50mm lens) in planing to use. Here in Sweden where I live its a rare occation to ride in temperatures above 5c (at the "dark time of year") guess that may help as well?


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## yetibetty (Dec 24, 2007)

God_Speed, as Lupine don't use a MaxFlex I would still say a big no on that one.
However if you have 50mm to play with(yes I did resist the joke) then maybe you could use the Hyperboost.

I would contact George at Taskled and see what he has to say, only he has the true answer.


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## God_Speed (Oct 5, 2007)

yetibetty said:


> God_Speed, as Lupine don't use a MaxFlex I would still say a big no on that one.
> However if you have 50mm to play with(yes I did resist the joke) then maybe you could use the Hyperboost.
> 
> I would contact George at Taskled and see what he has to say, only he has the true answer.


Thank you for the answer

Have been doing some calculating + reading I do now understand the extent of the heat problem. I've come to the conclusion that I'm best of going for a 4-led solution and maybe boost to 1200mAh instead. Think I'll wait for some nice 50mm Quad XP-G Optics and XP-G S2 leds to go on sale and then finish my project. My Hope Vision 4 will have to do for now


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