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Thread: Neophyte with some questions

  1. #1

    Default Neophyte with some questions

    I recently bought a modern li-ion 21700 light, and have a few questions.

    I'm coming from Nimh... so I have some quick catching up to do.

    I understand DIY'ing a light.. you can match driver type to Amps.. just not how many Amps go with what drivers in off the shelf lights: Zebra, Fenix, Acebeam, Nitecore, etc.


    My light is a Fenix Tk22UE with their 8A cell. I know the light doesn't use all 8 Amps.. based off of the SST-40 spec sheet, it's closer to 4 maybe 5 max.
    I know some might say 4A from 8A is fine but, that's around 50% capability of the cell, and it's too close for my liking.

    After dropping my light twice while using it, I checked the cell and saw it was dinged a little bit on both ends.
    It instantly made me think of some people here, and the risk of the protection circuit "possibly" being damaged when it needs to be charged.. I'm sure it's fine but... that little thought in the back of my mind.


    First question is:

    1. The light has a digitally regulated circuit, and a low voltage warning. So, if I made sure to pay attention the the L.V.W, or just the brightness step down.. is it okay to use unprotected cells with the addition of a D.M.M?

    2. Fenix just came out with a 10A cell, and I know I can use theirs but.. could I use anyone's 10A cell without harm? 10A is 10A, right?
    Or do I need to worry about the I.R. of cells, and risk blowing the driver from current availability?

    3. Is it safe to use any amp rated cell that's above what the emitter needs? I.E. 25 to 40 amps? I know there wont be an much of an improvement --if any.
    It'll just be at the lower end of it's performance curve.


    I have a charger in mind of getting.. a Vapcell S4 Plus.


    Okay.. crash course over.

  2. #2

    Default Re: Neophyte with some questions

    As far as i can see they made it to be used with both 21700 and 18650 batteries, you should be pretty safe running it with any quality battery as long as the amp rating is higher than the draw on it. If you decide to use other cells and you don't feel comfortable you could use a sacrificial cell and see how far down it drains an unprotected battery before it shuts off too and then decide if you want to use unprotected or not.

  3. #3

    Default Re: Neophyte with some questions

    Quote Originally Posted by Havok View Post
    I recently bought a modern li-ion 21700 light, and have a few questions.

    I'm coming from Nimh... so I have some quick catching up to do.

    I understand DIY'ing a light.. you can match driver type to Amps.. just not how many Amps go with what drivers in off the shelf lights: Zebra, Fenix, Acebeam, Nitecore, etc.


    My light is a Fenix Tk22UE with their 8A cell. I know the light doesn't use all 8 Amps.. based off of the SST-40 spec sheet, it's closer to 4 maybe 5 max.
    I know some might say 4A from 8A is fine but, that's around 50% capability of the cell, and it's too close for my liking.

    After dropping my light twice while using it, I checked the cell and saw it was dinged a little bit on both ends.
    It instantly made me think of some people here, and the risk of the protection circuit "possibly" being damaged when it needs to be charged.. I'm sure it's fine but... that little thought in the back of my mind.


    First question is:

    1. The light has a digitally regulated circuit, and a low voltage warning. So, if I made sure to pay attention the the L.V.W, or just the brightness step down.. is it okay to use unprotected cells with the addition of a D.M.M?

    2. Fenix just came out with a 10A cell, and I know I can use theirs but.. could I use anyone's 10A cell without harm? 10A is 10A, right?
    Or do I need to worry about the I.R. of cells, and risk blowing the driver from current availability?

    3. Is it safe to use any amp rated cell that's above what the emitter needs? I.E. 25 to 40 amps? I know there wont be an much of an improvement --if any.
    It'll just be at the lower end of it's performance curve.


    I have a charger in mind of getting.. a Vapcell S4 Plus.


    Okay.. crash course over.


    You should be fine relying on the driver's low voltage protection. Yes, using any cell capable of delivering the power that the driver requires is also fine. LED's are not black holes, they do not magically suck down current that is not available to them. If you have a cell rated to deliver 100 amps, that doesn't mean it instantly delivers 100 amps to whatever is connected to it (except in the case of a short circuit)...it means that it can deliver up to 100 amps without the voltage sagging below the normal operational voltage of the cell.

    The branded shrink wrap on a cell doesn't change the physics of the chemistry inside it, they may have a different protection circuit but aside from that they are just Li-Ion cells. Many are just re-wrapped cells from the big name manufacturers.

  4. #4

    Default Re: Neophyte with some questions

    Quote Originally Posted by lightfooted View Post
    You should be fine relying on the driver's low voltage protection. Yes, using any cell capable of delivering the power that the driver requires is also fine. LED's are not black holes, they do not magically suck down current that is not available to them. If you have a cell rated to deliver 100 amps, that doesn't mean it instantly delivers 100 amps to whatever is connected to it (except in the case of a short circuit)...it means that it can deliver up to 100 amps without the voltage sagging below the normal operational voltage of the cell.

    The branded shrink wrap on a cell doesn't change the physics of the chemistry inside it, they may have a different protection circuit but aside from that they are just Li-Ion cells. Many are just re-wrapped cells from the big name manufacturers.



    Thanks for the information. I thought I was being a little paranoid about some things.

    I admit.. I was reading about people playing stupid games, and winning stupid prizes by having 18650 cells achieve thermal runaway, and explode.

    Guess I payed too much attention to it.


    For the use any cell part.. I wasn't sure if Fenix snuck in something proprietary, like Olight did with their Warrior X Pro.

    Glad everything is good to go.

  5. #5
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    Default Re: Neophyte with some questions

    There are some cases where a high-amp rated cell is bad compared to a low-amp rated one. But you are not there, and probably never will be.

    There are some who want the absolute max possible from their lights. The so-called Direct Drive (DD) design connects the LED directly to the battery. Or as close to directly as possible in a flashlight with a switch, etc. This design depends on the internal resistance of various parts to limit the current to manageable levels. Take a reasonable DD light with an 8A rated cell, and swap out for a 100A cell, the much lower resistance of the 100A cell could spell doom for the LED.

    If you are not doing this, and the large majority of us don't, then the regulator (or driver as we tend to call them here) will control the current to the LED, which also controls the current drawn from the battery. Controlling the current is the driver's primary job, and most do at least an adequate job of it. They really don't care how much current is available, they only transmit as much as they are set for.

    So if you've heard some horror stories about high-amp cells, don't worry. You won't have problems.

  6. #6
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    Default Re: Neophyte with some questions

    It is definitely NOT true that one cell is the same as any other of the same chemistry and form factor.

    Some cells are optimized for high current capability. Some are optimized for high capacity. These two goals are unfortunately antithetical, given today's technology. High current cells have lower capacity, and high capacity cells have lower current ratings.

    There are also cells that are crap. Almost all (almost?) of the xxxFIRE cells available fall into this category. They will advertise 5000, 6000, even 9000 mA-H capacity in an 18650 cell, which is simply not possible today (as of this writing, the highest reliable rating I've seen is 3600 mA-H). If you buy a 9000 mA-H FandyFire cell, you are likely to get a 1400 mA-H garbage cell that won't perform or last well enough to justify even its pretty low cost, and won't be as safe as a brand name cell.

  7. #7

    Default Re: Neophyte with some questions

    Thanks for the information on drivers.

    Oh yeah, I've heard of those xxxFIRE cells. Always wanted to avoid those like the plague. I will be getting into DIY lights soon... there's something satisfying about knowing, and telling someone that you built your light.

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