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Thread: Keeppower 18350 protected vs unprotected.

  1. #31
    Enlightened Katherine Alicia's Avatar
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    Default Re: Keeppower 18350 protected vs unprotected.

    Quote Originally Posted by TimMc View Post
    Is 2.5V the discharge limit for most 18650/18350 3.7V cells?

    Would it damage the cell if you run them down to 2.5V a few times but mostly keep them charged between 3.6 and 4.2V?
    Yes, under 2.5v most chargers wont even "see" the battery and will refuse to charge it, the actualy danger occurs when they`re left at 2.5v or less for a while because metal needles can start to grow inside the cell and create a short. If the cell has only Just gone below 2.5 it is possible to safely bring them back but you have to be very quick! if they`ve been left standing below 2.5 then it`s best to get rid of them.
    I`v seen very old batteries brough back from less than a volt after being in a drawer for 5 years, but it`s Extremely dangerous! and just begging for trouble, trouble that can happen at random completely out the blue for no reason and usually involves lots of Fire!
    oh yeah, and it will reduce the overall capacity of the cell as well, so best not to go below 2.5 at all.

  2. #32
    Flashaholic*
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    Default Re: Keeppower 18350 protected vs unprotected.

    Depends on the cell. Always read the spec sheet. For example, Samsung 30Q can be drained down to as low as 1.0v, but they have to be recharged very slowly until above 3.0v. Below 1.0v, do not attempt to recharge. At least, that's according to the spec sheet. Different cells have different limitations.

  3. #33

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    Default Re: Keeppower 18350 protected vs unprotected.

    Just my 5 cents worth, this has been mentioned here a number of time now.

    Asked a similar question of a supplier and mentioned that I use my cells in line in a tube such as 2x18650 or 3x18650.

    Their response was a quite clear "we do not suggest unprotected cells for 2S and 3S applicaitons".

    Because I am lazy to do all the checking needed for safe use of unprotected, when I shop for new cells, its always for the protected variety.

  4. #34
    Flashaholic*
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    Default Re: Keeppower 18350 protected vs unprotected.

    Since you need an added button-top for series applications anyway, going the protected route isn't much of a hassle. But, yeah, if you choose to use unprotected, make sure to start with matched cells (same model, bought at the same time, and only used together). And, don't wait until the battery is almost drained before recharging (again, charge all of them at the same time and fully charge). If you do that, unprotected in series should be fairly safe. You'll still likely need a button-top version, though.

  5. #35
    Enlightened
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    Default Re: Keeppower 18350 protected vs unprotected.

    Is there a chart that shows acceptable ranges of IR for all different sizes of batteries that anybody is aware of?

  6. #36
    Flashaholic*
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    Default Re: Keeppower 18350 protected vs unprotected.

    Quote Originally Posted by Lights and Guns View Post
    Is there a chart that shows acceptable ranges of IR for all different sizes of batteries that anybody is aware of?
    The acceptable IR depends greatly on what your intended application is. It also depends on how you measure it. You can look at the spec sheets to see what the internal resistance should be for new (and genuine) cells, as well as how they measure it. For example, the 30Q states less than 26mR when measured with 1kHz AC after a full charge. IMO, that's kind of a useless measurement for flashlight users, since we're much more concerned with DC, but at least it gives you a baseline you can measure against as your cells get older.

    If you plan to use the cells in a high-drain light, then you probably don't want the IR to get much higher than that. If you plan to use it in a solar light, the IR can be ridiculously high. The only issue with high IR in low-drain applications, is that charging it can be difficult. The voltage goes up to 4.2v way before the cell is fully charged, unless you charge very slowly.

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