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Thread: First every DIY - (totally new)

  1. #1
    Join Date
    Oct 2018

    Default First every DIY - (totally new)

    Hello all!

    Completely new to all of this and staggered by all the options for DIY lighting. I want to make my own caving/mining exploration headlamp with a remote power source. I'm pretty good with soldering and wiring work, but not as good with maths and determining proper voltage, amps, etc. One thing I do know - I don't want to use C123 or regular batteries. I want to use 18650s! I want to make something that will run for a long time on high, and rechargable. Not too particular about distance. To be honest, something in between spot/throw would work.

    I was looking at the following:

    2x diode:
    2x driver:
    2x relfector:

    The problem is, I'm worried about making my own battery pack. I would like to find a pre-made waterproof pack, but I can't seem to find any that don't have a darn USB coming out for the power connection. I want to hardwire it to the light instead. The idea here is I want to make a little box with a clear cover, and mount two of these led's/drivers in it, and run a line to the power pack (perhaps in a backpack or belt holster). Ideally something where I can remove the cells and put them in a charger that will regulate and cut off as needed (rather than trying to wire in my own BMC).

    As an alternative, I'm looking at a nitecore HC90, but I wonder if I can build it to power from an external source of more than 1 18650? I am trying for runtime here...really hoping to get a full day's exploration out of one charge.

    And finally, this is a super amazing version of what I am trying to make:

    I would buy one if he was still here and I could afford it, but I cannot.

    Any guidance or advice welcome! Would prefer the DIY route for fun/learning.

  2. #2

    Default Re: First every DIY - (totally new)

    Welcome fellow spelunker!
    I have the Nitecore HC60, the little brother, but it is still fed by a single 18650. It really does have a long runtime, but I like the idea of a remote battery pack.

    As you well know, in caving two is one. You've got to have backups to your backups. It really is an amazing darkness inside a cave when you turn your torch off.

    As for a battery pack, why not look into those mini Pelican cases? They are about 4" long and totally waterproof. Toss a dual 18650 holder in it, running parallel, and you'd have a great start.

    A note here, I'd suggest staying away from Cree LEDs sourced from China. They are almost certainly fake.
    Look up MtnElectronics, Richard there is a big help if you need it, especially if you are considering making up a whole new torch, instead of just a battery pack.
    Have torch, will travel.

  3. #3
    Flashaholic* DIWdiver's Avatar
    Join Date
    Jan 2010
    Connecticut, USA

    Default Re: First every DIY - (totally new)

    I can certainly help you with the math.

    The 18650 is probably the best battery choice, because they give you the best bang for the buck. And you need a lot of bang.

    Since you chose a 3A driver and are going to use two LEDs, I'm guessing you want to run them at or near 3A. That means each LED is going to drain an 18650 about every hour, more or less depending on which cells you use. So the number of cells you need is about twice the number of hours you want the light to run.

    Also, the XML2 is getting a bit long in the tooth. I'd suggest a more modern device, like the XPL, XHP35, or even the XHP50.

    The lower Vf of the XPL would allow the light to stay in regulation as the battery voltage approaches 3V, instead of around 3.3 with the XML2.

    The XHPs would require a different battery configuration and driver, but that might be a good thing. The driver you selected is a linear driver. This means its efficiency is determined solely by the input and output voltages. With a Vf of 3.15 and an average battery voltage of 3.7, you'd get an average efficiency of 85%. A quality buck-type switching driver could bring that to around 95%

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