NEXTORCH - 300 m long-shot E6        
Results 1 to 10 of 10

Thread: 18650s in 2 C cell LEDs?

  1. #1

    Arrow 18650s in 2 C cell LEDs?

    I recently 3D printed adapters to run 2C and 3C cell LED lights on a single 18650, I figure there shouldn't be a problem with the 3 cells since they are designed for 4.5V nominal from alkalines, but what about the 2 cell version?

    Is the Voltage of an 18650 too much for a 2 cell C (or D) LED light?

    Anyone here have experience running 18650's in 2 cell C or D LEDs?


    Thanks!

  2. #2
    Flashaholic*
    Join Date
    Jun 2014
    Location
    Canada
    Posts
    2,652

    Default Re: 18650s in 2 C cell LEDs?

    It depends on the light. If it's a cheap light (such as a mag) that is depending on the internal resistance of alkaline batteries, then it might get over-driven if you use a high-power battery like an 18650, even if the (resting) voltages match. That will certainly be true if you're replacing a 2C battery, where the 18650 will be both higher voltage and higher power (low internal resistance).

  3. #3

    Default Re: 18650s in 2 C cell LEDs?

    What about LiFePO4? Not necessarily the sought-for solution for OP, or for most of us who are stocked with Li-ion 18650s, but I have given similar things some furtive, wispy thought now and then ...

    OP - is there room for a 3.3v voltage regulator in those 3D printed adapters? Why not adapt the voltage as well as the size?

  4. #4

    Default Re: 18650s in 2 C cell LEDs?

    Quote Originally Posted by x8353 View Post
    What about LiFePO4? Not necessarily the sought-for solution for OP, or for most of us who are stocked with Li-ion 18650s, but I have given similar things some furtive, wispy thought now and then ...

    OP - is there room for a 3.3v voltage regulator in those 3D printed adapters? Why not adapt the voltage as well as the size?
    I thought about LiFePO4's, should work better in the 2C adapter, but I don't have any in 18650 size.

    Good idea about building a Voltage regulator into the 3D print! I had not thought of that. As it is now, the adapters are just a 2 or 3 C cell sized tube with a hole for a 18650 in the rear and a smaller hole through the front for a brass bolt to make the positive connection.

  5. #5

    Default Re: 18650s in 2 C cell LEDs?

    I checked the current on some low cost 3C lights: a Defiant 850 lumen triple LED, a 200 lumen Rayovac "Indestructible" and a Mag ML25 - all draw the same current from a 18650 as they do off of Duracell Ion Core NiMH's (which is what I normally use in C cell lights place of alkalines), so I don't see a problem with a single 18650 in a 3C light that can handle NiMH's.


    I am still researching of use 18650's in a 2C Mag ML50LX, apparently the 2D ML300 uses a buck/boost driver which should be OK up to around 5 Volts, if the 2C cell ML50 has the same driver, it should be good to go as well.

  6. #6
    Flashaholic* fivemega's Avatar
    Join Date
    Jan 2003
    Location
    California
    Posts
    4,563

    Default Re: 18650s in 2 C cell LEDs?

    By my experience, most of modern LED flashlight driver can tolerate 50%~60% extra input voltage so single 18650 will be OK on 2 cell ML50LX

  7. #7
    Flashaholic* Timothybil's Avatar
    Join Date
    Nov 2007
    Location
    The great state of Iowa
    Posts
    3,157

    Default Re: 18650s in 2 C cell LEDs?

    Why not use 26650 cells for the additional capacity?
    Remember, Two is One, and One is None!.

  8. #8

    Default Re: 18650s in 2 C cell LEDs?

    Quote Originally Posted by fivemega View Post
    By my experience, most of modern LED flashlight driver can tolerate 50%~60% extra input voltage so single 18650 will be OK on 2 cell ML50LX
    Thanks much for the info - very much appreciated!

  9. #9

    Default Re: 18650s in 2 C cell LEDs?

    Quote Originally Posted by Timothybil View Post
    Why not use 26650 cells for the additional capacity?
    2 reasons:

    1 - I don't have any 26650's at the moment.

    2- I am not sure if 26650's would fit in the C cell lights that I have?

    I actually printed a 2C to 2D adapter (so that I can use the 18650 to 2C adapter in a 2D light). I left the diameter of the 2C cell chamber on the large side so that 26650''s could be used in 2D cell lights in the future, but I would have to make another adapter to bridge the length difference between 2C cells and a 26650 to make contact.

  10. #10
    Flashaholic* fivemega's Avatar
    Join Date
    Jan 2003
    Location
    California
    Posts
    4,563

    Default Re: 18650s in 2 C cell LEDs?

    Quote Originally Posted by Timothybil View Post
    Why not use 26650 cells for the additional capacity?
    26650 will not fit inside "C" barrel without boring.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •