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Thread: What are 18650 cells?

  1. #1

    Default What are 18650 cells?

    I am checking out the new Jetbeam lights that take an 18650 rechargeable. I am just curious if those are like the double cr123? Is the its own special form factor, so I couldn't use primaries in this light?

  2. #2
    Flashaholic*
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    Default Re: What are 18650 cells?

    These cells are 18mm diameter and 65mm long. They are a little fatter than a CR123 and I believe the same length as 2 123's placed end to end.

  3. #3

    Default Re: What are 18650 cells?

    So then would it be possible to run two 123s in one of these new Jetbeams if that was all I had on hand and I didn't have a charged up 18650?

  4. #4

    Default Re: What are 18650 cells?

    ...correct. But mind that 18650 have around 3.6 volts, whereas two 123 in series have 6 (primary) or 7.2 volts (rechargable).
    Regards, Alex
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  5. #5
    Flashaholic* mighty82's Avatar
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    Default Re: What are 18650 cells?

    Quote Originally Posted by 4EN[sic] View Post
    So then would it be possible to run two 123s in one of these new Jetbeams if that was all I had on hand and I didn't have a charged up 18650?
    No, you can't run primaries in it. That will probably blow the circuit. They are single cell only. (I'm talking about the Jetbeam lights now)

  6. #6
    Flashaholic*
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    Default Re: What are 18650 cells?

    Hello 4EN[sic].

    I must for those who want to learn about different cells is this: MDs Lithium-Ion>Incandescent guide, +compatibility/comparison chart
    and this: MDs Rechargeable Compatibility chart/guide for popular flashlights!

    Anders

  7. #7

    Default Re: What are 18650 cells?

    I will check that out. Thanks for the help.

  8. #8
    Flashaholic*
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    Default Re: What are 18650 cells?

    4EN[sic], if you are referring to the JetBeam Jet-III listed here, the input voltage for that light is: 0.7-4.2V, so you can only run 1x18650 (max: 4.2v, nominal voltage: 3.7v) and NOT 2xCR123's - as indicated by mighty82, running 2xCR123's would be 7.4v so that would exceed the voltage of the light.

    Anders, you beat me to it - good call.
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  9. #9
    Flashaholic* Fallingwater's Avatar
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    Default Re: What are 18650 cells?

    Quote Originally Posted by 4EN[sic] View Post
    I am just curious if those are like the double cr123?
    Size wise they are about as long as two CR123s and two mm thicker. Capacity wise, a single 18650 has about twice the energy of two 16340/RCR123 (rechargeable CR123s), sometimes more.

    Is the its own special form factor, so I couldn't use primaries in this light?
    Hardly special. 18650s have been used for ages in laptop battery packs and other things where energy density is more important than small size. Before they became common enough that sites like DX started selling them, the main source for hobbyists and tinkerers was, indeed, dismantled laptop packs. I've recovered a few old but still serviceable cells from discarted laptop packs myself; they usually have at least half of their cells with useable capacity left.

    There are no primary 18650s, because there is virtually no market for them so nobody bothers making them.
    Eat, drink and be merry, for tomorrow you may die.

  10. #10

    Default Re: What are 18650 cells?

    is 18650 same as a (AA)rechargable battery

  11. #11
    Flashaholic* TONY M's Avatar
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    Default Re: What are 18650 cells?

    Quote Originally Posted by iluvflashlight View Post
    is 18650 same as a (AA)rechargable battery
    No. The 14500s are basically AA size lithium rechargeable cells. 18650s are much bigger and not compatable.

  12. #12

    Default Re: What are 18650 cells?

    It's important to note that 14500 cells, while the same size as AA, will cook most AA equipment, since they run at around 3.6v. When people talk about "AA rechargable" cells, they usually mean NiCd or NiMH, which run at around 1.2v.

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