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Thread: 12v xhp70 led

  1. #1
    Unenlightened
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    Feb 2019
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    Default 12v xhp70 led

    Hi guys, this is my first post and I'm looking for some good information and direction.
    I am wanting to use a Milwaukee m18 flashlight (2735-20) plan is to swap out the led to a xhp70 12v 2.4a, now what will be needed to properly run this led? I'm assuming I need to start with the m18 battery to a regulator down to 12v to a driver then the led. Is that correct or am I missing something?

  2. #2

    Default Re: 12v xhp70 led

    Quote Originally Posted by Zackk44 View Post
    Hi guys, this is my first post and I'm looking for some good information and direction.
    I am wanting to use a Milwaukee m18 flashlight (2735-20) plan is to swap out the led to a xhp70 12v 2.4a, now what will be needed to properly run this led? I'm assuming I need to start with the m18 battery to a regulator down to 12v to a driver then the led. Is that correct or am I missing something?
    Hint- You will likely get much more help if this is posted in the "custom and modified" section of the forum.

    Example of another M18 light conversion is at;
    http://www.candlepowerforums.com/vb/...th-Cree-XML-T6

    Normally, if using a battery pack with more voltage than is needed by the LED, you would use a "buck" driver to drop the input voltage from 18v input to 12v output and to further control the flashlight but this 18v to 12v (5S to 4S) step-down does not appear to be a common need within the LED flashlight world and I do not quickly find any easily available flashlight specific buck drivers configured for this stepdown interval that would give you all the programmable light steps and features. If you are OK with just a single output level on/off light (no steps), you likely could wire in a general electronics (non flashlight specific) adjustable output DC buck converter to direct drive the LED, search for "LM2596 DC to DC Buck Converter" for relevant examples and experiment with the voltage setting to make sure to not drive the LED so hard that it over-heats.

    Or, if you do want to have more control with programmable light levels, it should work to output the 12v from the separate buck converter into a flashlight specifi"c direct drive" FET driver properly configured for 4S battery input that would then have capability to use PMW to step down the light output intervals further. search on "mountain electronics FET/DD" for relevant examples of such a driver that can be ordered configures for 4S battery input.

    Alternately, you could DIY build your own simple adjustable constant current regulator circuit following the general example at; https://www.instructables.com/id/Cir...h-Power-LED-s/
    I've built and bench tested this constant current circuit from scavenged parts, it seemed to work fairly well to direct-drive a light I had with a 3X series of LEDs.

    I would assume that the Milwaukee battery pack already includes low voltage protection to prevent running the LION battery excessively low but it is probably a good idea to confirm that is the case.

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