# Dual XPG, XML Hiplex build, thoughts please



## emu26 (Jun 23, 2008)

OK, because of DX wonderful (joke) customer service I find myself with a a few spare of these drop ins. I have also ordered an xml drop in with what looks to be a similar reflector. I have on hand a hiplex driver that has been sitting waiting for a project for sometime now.

I'm thinking of building a three up helmet light and running two parallel driven xpg in series with a single xml @ 2.8A, the max output for the driver.

If I'm right the two xpg should see 1.4A each and the xml should see 2.8A, yes?

Is there anything I should be concerned about, apart from blinding the poor local wildlife?

How do I work out run time for this type of configuration?

Given that the hiplex needs +0.5v overhead 2 2.8A would I be able to run this off a 7.4v battery?

Thanks in advance


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## ortelius (Dec 6, 2007)

emu26 said:


> If I'm right the two xpg should see 1.4A each and the xml should see 2.8A, yes?


Yes.


emu26 said:


> Is there anything I should be concerned about, apart from blinding the poor local wildlife?


I think it should be fine. Except, of course, in case that one of the XPGs says good-bye (for whatever reason), the other one will follow it almost instantly......


emu26 said:


> How do I work out run time for this type of configuration?


Think of it as all three leds are being driven independently and then sum up their power consumption.

Let's assume XML @ 2.8A has Vf around 3V, that is 8.4W.
Let's assume XPG @ 1.4A has Vf around 3.2V, that is 4.5W for one, 9W for two of them.
So, all together 17.4W.
Now, calculate how much Wh (Ah x V) your battery offers, account for some losses in driver and wires, divide that with leds power consumption and you have it...


emu26 said:


> Given that the hiplex needs +0.5v overhead 2 2.8A would I be able to run this off a 7.4v battery?


Yes, it would be fine. Hipflex will see a Vf of one XML and one XPG as the output Vf, which should be around 6.2V. So, only at the very end of the battery discharge curve it should switch to direct drive, the main part of the curve it should be well in regulation.


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## emu26 (Jun 23, 2008)

Thanks Ortelius.

I was aware of the dangers of losing one xpg and the impact it would have on the other. One thing I hadn't considered though was if I do loose both xpg do I by default also loose the xml because no power will flow the xpg to the xml?

If that is the case is it possible to run a bypass cable around the xpg to the xml. Have it switched with a simple on off clicky switch. Keep the switch off all the time but if something goes wrong with the xpg, or I just want to run with the xml, turn the switch on?

Thoughts anyone?


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## ortelius (Dec 6, 2007)

emu26 said:


> One thing I hadn't considered though was if I do loose both xpg do I by default also loose the xml because no power will flow the xpg to the xml?


Actually no, your XML will survive that situation just fine. I'm not sure how bunt-out LED behaves: does it act s an open circuit or as a short circuit. In first case, if both XPGs leave the output circuit open, then no current will go through XML, so no harm will be done (except that you'll be left in a total darkness  ). On the other hand, if dead XPGs behave as a short circuit, then driver will still provide the same 2.8 A of current on the output, so your XML will continue to work, as if nothing has happened. Of course, the driver's efficiency will be worse (because the output Vf will be halved), but as long as the driver can cope with the additional heat caused by that decrease efficiency, your XML will never know that its neighboring XPGs are dead.

EDIT: Actually, given it a second thought, it is obvious that burnt-out XPG will behave like an open circuit, otherwise first dead XPG would not cause the second one to die, too. So, in such a situation, you'll be left with non-functioning light, but no harm done to your XML.


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## emu26 (Jun 23, 2008)

It was the being left in total darkness that I was referring to and why I was suggesting / asking about the bypass so that if the dead xpg stopped the juice flowing through to the xml I could flick a switch and provide an alternate route.

Thanks


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## ortelius (Dec 6, 2007)

emu26 said:


> It was the being left in total darkness that I was referring to and why I was suggesting / asking about the bypass so that if the dead xpg stopped the juice flowing through to the xml I could flick a switch and provide an alternate route.


:aureola: Sorry, I've read your question too superficially. rft:

Yes, your plan with a switch in a bypass should work just fine. But I doubt it is worth the trouble. I have couple of my lights that have leds in parallel configuration and never have had any problems with them.

Unless, of course, you want to use that second switch also for additional dimming purpose (turning both XPGs on/off at will). But with such an advanced driver, there is probably no need for this either.


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## Goldigger (Nov 6, 2009)

Could you not get around this problem by using a lflex to drive the two xpg's?
assuming you have room for two drivers?
I was going to suggest using 2 lflex one for the xml and one for the two xpg's...but not sure that will work for the xml because of your 2S battery..


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## emu26 (Jun 23, 2008)

Thanks guys.

Goldigger I already have the hipflex with no other project in mind for it and would like to keep this build cost to a minimum (as far as new outlay is concerned).

As for the battery I have a handful of old 12v NiMH which are almost on their last legs and a couple of 14.8v li-ions. I asked about the 7.4v simply because I am also building another twin DX b2flex helmet light which I plan on getting some small batteries for so I can put them on my helmet.

Problem is as I type this I suddenly remember that the new b2flex require much more over head than the old bflex and I don't think they'll run a twin xpg from a 7.4v battery


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## P220C (Jan 31, 2011)

I read this a few days ago, and it might apply to your question.

"Electrical overstress (EOS) is often associated with catastrophic failures...

Beyond a certain threshold, a single-pulse event will lead to an immediate catastrophic failure of the LED. In this case, there are two general failure modes: *either a short circuit or an open circuit.*"

Cutter. "Pulsed Over-Current Driving of XLamp LEDs.Information and Cautions." Cree: Application Notes.: (2010-2011) Online. http://www.cree.com/Products/pdf/XLamp-Pulsed-Current.pdf


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## emu26 (Jun 23, 2008)

Yeah, 1 month down and the xml has finally shipped, although still no tracking number


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## emu26 (Jun 23, 2008)

Mr Postman arrived today. 

Quick beam test against the ceiling with a couple of "jerry" rigged AAA batteries shows a nice even hotspot, a couple of rings around it, which should be lost with the xpg beam, and a fairly tight spill, even tighter than the DX xpg pill I used previously.

Sorry no pics, it drained down the batteries too quickly.


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## mfj197 (Jan 28, 2011)

emu26 said:


> If I'm right the two xpg should see 1.4A each and the xml should see 2.8A, yes?


My only concern would be that the forward voltage of the two XPGs might need to be pretty evenly matched. The one with the lower Vf will be sinking more of the current than the one with the higher Vf. The HipFlex wouldn't know - it's going to send 2.8A between the two, but if one is sinking 2A and one 0.8A then there might be problems. Doubt it would be that extreme though.


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## Itess (Feb 22, 2009)

Still no pics? Useless thread...


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## emu26 (Jun 23, 2008)

mfj197 said:


> My only concern would be that the forward voltage of the two XPGs might need to be pretty evenly matched. The one with the lower Vf will be sinking more of the current than the one with the higher Vf. The HipFlex wouldn't know - it's going to send 2.8A between the two, but if one is sinking 2A and one 0.8A then there might be problems. Doubt it would be that extreme though.


Yes, that is one of the problems with paralleling LEDs. Still happy to roll thee dice with this one though. Everything except the xml pill was "stock on hand" 

Itess, be patient my boy, be patient


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## emu26 (Jun 23, 2008)

There you go itess, videos are better than pics, but I'm not game to hit those links


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## vroom9 (Feb 24, 2009)

mfj197 said:


> My only concern would be that the forward voltage of the two XPGs might need to be pretty evenly matched. The one with the lower Vf will be sinking more of the current than the one with the higher Vf. The HipFlex wouldn't know - it's going to send 2.8A between the two, but if one is sinking 2A and one 0.8A then there might be problems. Doubt it would be that extreme though.


The problem is even worse that that. Remember that Vf decreases with temperature. What happens is that one LED draws a bit more current and that heats it up. This becomes a cycle and one LED will hog more current. However, resistance in the circuit and the LED itself helps fight that effect. I would consider adding a tiny amount of resistance to help ballast the two XP-G's that are in parallel. You should only need a voltage drop of .05 to .1 volt to balance the LEDs. That's only 66 milliohms in series with each XP-G for that .1v drop at 1.5 amps.


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## emu26 (Jun 23, 2008)

Thanks Vroom, I have read about using resistors before to help balance parallel strings but never really understood.

Will one resistor before the cable splits to the two LEDs be enough or should I put a resistor between where the cable splits and each LED?

In simple terms if for a non electronics person, how does this help the leds stay balanced?


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## vroom9 (Feb 24, 2009)

emu26 said:


> Thanks Vroom, I have read about using resistors before to help balance parallel strings but never really understood.
> 
> Will one resistor before the cable splits to the two LEDs be enough or should I put a resistor between where the cable splits and each LED?
> 
> In simple terms if for a non electronics person, how does this help the leds stay balanced?


The resistors need to be in series with each LED so you need two resistors and they need to go between where the cable splits and the LED. With only a tenth of a volt of drop the LEDs will need to be as close to the same temp as possible. Try and design it so each LED has more or less the same geometry as far as heat sinking goes so they run at the same temperature. If you are going to build it three in a row that would mean putting the XM-L in the center.


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## Vancbiker (May 25, 2005)

I have done a few lights using two series wired MCEs in parallel. None have had any problems yet. Have I just been lucky, or is the parallel balance problem not All that much of a problem?


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## emu26 (Jun 23, 2008)

Vancbiker I believe the theory behind it is sound but I'm not sure its enough to have me concerned, yet. It probably will be if I don't protect against it and I have problems.

Anyway, day one on my lump of Al.

A tad under 300gms on the scale at this point in time







No work shop for me so about 3 hrs to this point including setting up, packing up and cleaning up







That time includes this housing which will replace my "cheap torch" that I have constant problems with








Stay tuned, but don't hold your breath. Hopefully they'll both be done in time for The Mont.

Of topic, any other Aussies doing The Mont this year?


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## P220C (Jan 31, 2011)

I'm runnng two XPGs in parallel up to 3.2 Amps for the pair and have not noticed any color shift or other indicators that there is a problem.

Granted these emitters were bought as a connected pair from cutter, so I would assume (I didn't test) that the VF are fairly close.

Another caveat, I have temp sensing set to 50°.


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## Toaster79 (Apr 5, 2010)

Emu those are looking interesting! Can't wait to see the finished light


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## emu26 (Jun 23, 2008)

Day 2, add another 2 1/2 hrs. All holes for fixing front and back plates to both lights drilled and tapped. Drilled the o ring lip for the small light. Started drilling the hole for the driver. Dressed the front and back of the big light

No pics today, sorry. Maybe some tomorrow after day 3


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## emu26 (Jun 23, 2008)

Day 3, + 2 hrs

Small light body now all but complete, still need to tidy up the top grooves which I have done by hand (last time I tried to groove a block this small it cost me a saw blade.)






















Day 4 +1.5hrs

Big light, new face plate cut and drilled, I like to cut twice and measure once  
Holes for DX pills drilled but not yet milled








Lesson, never try to pick up a block of al that has been under the drill press for about 30 mins :madman:


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## yetibetty (Dec 24, 2007)

Emu, I like the look of this Big light of yours. I assume you used hole saws. 
I still have burn marks on the floor boards from using them when I picked the Ali up straight off the drill press and dropped it as quick as I could.

Nice work, looking forward to seeing it finished.


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## odtexas (Oct 2, 2008)

Coming along nicely.


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## emu26 (Jun 23, 2008)

Thanks guys.

Yes, hole saw used for the outer edge of the drop in recesses. I'll take out the rest with the end mill bit in the drill press. Fortunately for me I didn't get a good enough hold of it to move it off the drill stand, so just a couple of minor burn marks on thumb and forefinger. what's that saying, "Skin grows back"


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## savagemann (Jan 14, 2008)

Looking great man.
I'm about to setup a little workspace and make a bench.
Will be mounting my drill press and grinder. I'm sure they'll see alot of use.
Can't wait to see these buggers finished EMU.


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## emu26 (Jun 23, 2008)

Gosh it gets slow having to take the piece out of the clamps to remove the swarth all of the time so that you can see what your're doing as you mill down into the body of the light.








There has to be an easier way, I know how about drilling a relief hole through the side of light body to let the swarth out.








Aaarrrggghhhhhhh :madman: :madmax:  








If only it were the bottom I could bog it up and hide it under the mount.

Bye for now, while I go off to lick my wounds


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## odtexas (Oct 2, 2008)

:incazzato: :cryin:
Been there, done that, know the feeling.


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## troutie-mtb (Sep 20, 2007)

emu26 said:


> Gosh it gets slow having to take the piece out of the clamps to remove the swarth all of the time so that you can see what your're doing as you mill down into the body of the light.


Simples use a vacuum cleaner and suck as you mill 

is that case now fubared Stu


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## Goldigger (Nov 6, 2009)

troutie-mtb said:


> Simples *use a vacuum cleaner and suck as you mill*
> 
> is that case now fubared Stu


Thats exactly what i do 

Im a bit behind here..did you buy a mill Emu?


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## emu26 (Jun 23, 2008)

No mill yet Goldigger, went very close to pulling the trigger on that baby proxxon but when postage costs as much as the machine I get a little pissed. Probably for the best, 3mm max mill size would take ages to mill out a housing like this. Still using the trusty drop saw and drill press (which doesn't like me very much at the moment.

Troutie, clearly I do suck as I mill, hence the nice new shiny paper weight my daughter now has. So not completely fubared, just not usefull for its original purpose.

Version 2 is in the making


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## savagemann (Jan 14, 2008)

Man, that sux EMU.
It was looking pretty tidy.
Any design change on V2?
Gonna use a vacuum this time?


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## yetibetty (Dec 24, 2007)

Emu, that's a shame after all of that work.

When I used to make my drill press pretend it was a lathe I would start the hole with the largest hole saw just as you did but then switch to progressively smaller hole saws as this makes milling out the waste very easy at the end and you won't have to mill close to the edge of the housing. 

This was however, for 35mm holes and in your case you might be starting off with your smallest hole saw.


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## emu26 (Jun 23, 2008)

No design changes to speak of with version 2 savagemann other than relocating two of the rear screws back to where they were originally drawn, that was mistake No1 with the first attempt, oh, and of course, version 2 won't have the top mounted air vents to let out the heat from the hipflex 

Yeti, I did start with the 25mm hole saw, I need 25mm for the reflectors with a small lip at about 26mm for the very top edge, but on version 1 I "milled" out everything after that. Version 2 I am taking out more with progressively smaller hole saws. I can step all the way down to about 16mm without leaving any little flanges and I will then bulk out the rest with the good quality end mills I got from that UK engineering supplies place.

I made the cock up when I was milling out a 10mm x 36mm hole all the way through the body for the hip flex. Somehow the table had slipped off square to the bit. I'll be checking that bolt a little more frequently from now on.


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## emu26 (Jun 23, 2008)

Ground hog day 









Atleast this one is on the bottom edge and is where the thickest part of the reflector is so it might be salvageable.


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## mfj197 (Jan 28, 2011)

I feel your pain emu26.


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## emu26 (Jun 23, 2008)

To rub salt into my wounds it would appear that I have slightly over drilled one of the hole saws while I had the pilot drill still attached resulting in a hole about 6mm across and about 2mm deep right in the center of the pocket that will house one of the xpg pills. The brass pill is about 20mm across.

I was thinking of either filling it with B weld and then grinding it back to a flush finish with the rest of the pocket or maybe sitting the hole block on the ceramic cook top, heating it, and then filling the hole with solder and grinding that smooth. 

Any thoughts on either of these options or is it a bit of overkill given the pill is still so much larger than the hole?


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## emu26 (Jun 23, 2008)

Well, after giving you all a very valuable lesson in how not to make a light body I am pleased, no make that relieved to say that the body is 95% done. Need to make the threads deeper for the face plate screws after I had to take a mil or three off the face and there is still some tidying up to do around the rear cover.

If I ever mention on this forum that I am contemplating another build like this before I acquire a mill, will someone send me a reminder to this thread, or just shoot me? Thanks in advance (I know the addiction is too strong to be overcome)

Anyway, I know many of you like to name your lights and many great engineering marvels kind of adopt a name of their own during construction. Well, this is no engineering marvel but it kind of adopted its own name during the manufacturing stage. It was a close run thing between "You stupid f#$k", "Ahh, you f#$king idiot" and the eventual winner by sheer default on the number of times it was heard from the depths of the garage, "You mother f#$ker"

So here is "You mother f#$ker"









More shots when it is complete, probably next week sometime and beam shots in about 2 weeks from the usual spot.


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## odtexas (Oct 2, 2008)

emu26 said:


> "You stupid f#$k", "Ahh, you f#$king idiot" and the eventual winner by sheer default on the number of times it was heard from the depths of the garage, "You mother f#$ker"
> 
> So here is "You mother f#$ker"


I seriously can't stop laughing at that.....


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## yetibetty (Dec 24, 2007)

Well done Emu:thumbsup: After seeing the last picture that you posted   I thought that there would be no way of tidying it up. If you can manage that on a drill press then you have skill.

You *deserve* a milling machine.......Hint.... Hint....


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## emu26 (Jun 23, 2008)

and it lives up to its name, "You mother f#$ker"







I don't get how the xpg's light up but the xml doesn't.  
+ve led on the hipflex to the positive pad on the xml, -ve pad on the xml then splits and goes to the two +ve pads on the xpg's, -ve pads from xpg's both come back to the -ve on the hipflex.

Any thoughts?

Odtexas, I'm no longer laughing :cryin:

Yetibetty, if I had skill it would never have looked like that in the first place. I call it blind stubbornness, or is that stupidity that gets it from the previous pic to this








It's late, I'm off to bed most unhappy


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## Vancbiker (May 25, 2005)

I know it's bad form to laugh at someones misfortune, but I have to admit that your description of the name selection process had me going. 

Jumper out the XPGs to see if the XML works on its own. That will tell you if it is bad or if the series/parallel arrangement is the problem.

BTW, the housing is not bad. Especially considering the tools used to cut it. Get yourself in front of a real mill and the results will be awesome.


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## yetibetty (Dec 24, 2007)

Emu, it could just be down to reflection but it looks like your XM-L has a slight glow.


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## emu26 (Jun 23, 2008)

Yes, I noticed that in the pic as well but there is nothing there. I think it might just be a bit of refracted light as all three glass lenses touch each other so there will be a bit light transference in that.

something funny is going on though. brand new hipflex, well unused at least power on for the first time the leds should see 1A, so each xpg would see 500ma, they don't appear to be anywhere near bright enough for that.

Oh well, no time to fix it now before this weekends race, will have to wait for tinkering next week sometime.


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## emu26 (Jun 23, 2008)

and it's cuboid little brother just earnt the name "Oh for f#$ks sake!"

Lucky I have spare lights.
:madmax: :madman: :madmax: :madman:


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## troutie-mtb (Sep 20, 2007)

Have you checked the xml is still OK .
I had to try your configuration to see if it worked OK and yep as expected all three leds lit up at 5 volts on the power supply ramped up to 3 amps and 6.7 volts .

so got to thinking about the set up wonder what the beam would be like for a cute triple ss
with 1 xml and 2 xpgs might give it a go this weekend .


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## emu26 (Jun 23, 2008)

No mate, was pushed for time yesterday packing to go away. Am currently sitting in the middle of a paddock enjoying a cuppa and waiting for tram mates to show up. 

Those numbers are looking good for a decent run time. I will pull it apart one night during the week and test things.


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## emu26 (Jun 23, 2008)

Chris, did you get to play with the beam?

Haven't had a chance to touch this yet, so still not sure what the prob is but I do suspect a dead XML


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## emu26 (Jun 23, 2008)

Well, 

I learnt a valuable lesson tonight, when you are tired and pushed for time, don't even attempt to do complex tasks. This was the case last week.

Tonight, a completely different story. I took the front cover off and the first thing that hit me was that the solder joint where the two wires come back from the xpg's and join to the wire going to the -ve on the hipflex was right at the front of the light body, almost jammed between the top edge of the xml reflector and one of the connections to the driver. It was also obvious that some of the liquid insulation had come off. I pulled the wire forward, out of the housing, connected the battery and hey presto








So, I disconnected the battery, applied several coats of liquid insulation to the offending solder joint, took off the back cover and applied more to all of the connections in there as well, connected the battery and it still worked. 

Applied thermal grease to front and back covers, closed "You Mother F#$ker" back up and.......it still worked  

Made a cuppa, and sat down with the manual. 10 Minutes later  damn these things are bright.

Beam shots next week when I'm not batching with three minors.

BTW, I'm not surprised about the cause of the problem, it's tighter than a can of sardines in there. Took about 45 minutes with a shoe horn to get it squeezed in there in the first place. Should have made it an hour and saved some headaches.


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## yetibetty (Dec 24, 2007)

That has turned out to be a rather nice light:thumbsup: Are you happy with what you have seen of the beam so far?


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## mfj197 (Jan 28, 2011)

Nice one emu26! Very nice.


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## emu26 (Jun 23, 2008)

Thanks.

Haven't really tested the beam properly yet and I'm wary about first impressions because I have been misled by them in the past, but in a word *YES* 

Ceiling bounce test has the hot spot slightly smaller than my triple regina xpg, (a good thing by me as I find the regina too wide for liking) but slightly wider than my mates double xpg with the same reflector that I built earlier this year. It has a similar spill pattern to the regina's but again marginally smaller and probably a little more defined at the edge, which know won't appeal to all.

In the back yard there is a noticeable difference in illumination of some gums 5 houses up the road, about 100m, when compared directly to the regina at 1.5A. Obviously trail testing will be the ultimate decider.

One thing I'm not sure about is I have both the regina and this in duomode UIB2Q so I have a full tilt and a low setting. With the regina, driven by a B2flex, I can hold the switch to turn it off, it flashes before it goes off. from here it will either turn off or go to a very low level which is ideal for standing chatting or fixing a mechanical. This light doesn't seem to do that, a press of the switch turns it off. Any idea's as to what I have missed in the programming, this light has so much output that I think ultra low would be very handy.


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## mattthemuppet (Jul 16, 2004)

does the hipflex do threemode? I find that very handy for this reason - L1 for trail side stuff, then switch between L4 > L5 for riding.

no idea why press = off. Have you double checked you have it in UIB2Q?


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## yetibetty (Dec 24, 2007)

Don't think the hipFlex has threemode. But it should be the usual hold button down for 2 seconds to turn off.

Once again, great light.


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