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Discussion Starter · #1 ·
hi!

I am thinknig of what I was going to get for my next helmet light (I currenty run a 2x XRE) I have a nice hand torch that I could turn into a ligtweight 4x XPG driven by a bFlex that is in my 2x XRE. Do you guys think this light would be worth the $$$ and the time or I should get a magicshine and save the trouble?

Thanks!
 

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As you have a bFlex that you can use and an mr11 housing then you could have a possible 1200 or so lumens on your hands with the XP-G option.

The Magicshine has around 600/700 lumen.

As long as you are sure the torch can handle the heat, then I would go for it.

Cutter do an mr11 quad optic and quad XP-Gs pre mounted.
 

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If you go with 4 XPGs, what battery do you intend to use? If it's going to be Li-Ion/Li-Po, you'll need at least 5 cells in series, if you want to keep the light in regulation with bFlex for the whole discharge cycle. Unless of course you want to configure your leds in 2S2P, but in that case each led will get just half the current (max 500 mA) from bFlex.

Keep that in mind as 5S batteries (and corresponding chargers) are somehow "exotic" and not so easy to get.
 

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Discussion Starter · #6 ·
Hum... I had a pic of my torch around but can't find it....

Is heat going to be such a problem? I intended to drive it at 750mA max.

And yes, I saw the Cutter kits, I would order a 25mm 4x XPG-R5 PCB, the MR11 optic and a few 10mm square individual optics in case the MR11 doesn't work out for me.

As batteries goes, I tought that 4x 18650 cells would do the job....
 

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Billabang said:
As batteries goes, I tought that 4x 18650 cells would do the job....
Umm, not quite. At 1000mA, the Vf of XPG led is around 3.3V. So, 4 leds in series means 13.2V of total Vf.

For bFlex to remain in current requllation, you need input voltage to be at least 1.1V higher (for 1000mA output) than total Vf. So, your input voltage should be at least 14.3V to keep it in regulation.

With 4 18650 cells in series, your input voltage will vary from 16.8V (fresh from the charger) to 12.0V (when cells are nearly empty and should not be further discharged any more). So, only for about first half of the discharge your driver will be in regulation, for the remaining part your leds will be directly driven from the battery.
 

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Billabang said:
And yes, I saw the Cutter kits, I would order a 25mm 4x XPG-R5 PCB, the MR11 optic and a few 10mm square individual optics in case the MR11 doesn't work out for me.
I've used both the quad setup your describing and the MR11 triple setup with Cute-3-xp optic. I would recommend you go with the triple. The optics on the quad really aren't very good compared to the triple. You'll end up with as much useable light actually on the ground with the triple and it'll run great off a 4 cell pack, with a longer run time and less heat. I use a triple on both the bar and the helmet and I end up running them at half power 95% of the time and it's still more light than I really need.
 

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BatterySpace has a 5-cell 18.5volt 18650 battery but it ain't cheap ( $85 ). Not to mention that all of their batteries have gone up in price in the last couple years. Probably best to buy one of the DIY battery holders and use that, of course that is if someone makes a five cell holder. Another option might be to buy one from Daniel at HIDtech as he uses 5-cells for some of his builds. Not sure but I think he builds his own batteries. The 5-cells that I have from him work fine.

Links > http://www.batteryspace.com/185vli-ionpackmodules.aspx
http://www.hidtechnologies.com.au/index.php
 

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Discussion Starter · #10 ·
Oh these hidtech lights are nice...

as batteries goes, I want to make my own 18650 holder, I have many spare parts that would work, I only have to decide 4 or 5 cells...

as for 3 leds vs 4.... I didn't think bout that one.... I tought more is better : )

Is it wiser to use individul 10mm optics or 3-xp ones? I tought the 4 up ones were good...
 

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Billabang said:
as batteries goes, I want to make my own 18650 holder, I have many spare parts that would work, I only have to decide 4 or 5 cells...
I have made 18650 holders from scratch and also using the Digikey holders in this thread...

http://forums.mtbr.com/showthread.php?t=573341

Using the Digikey holders is easier and faster and make a very nice battery setup.
 
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