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Thread: Does this light need a protected battery?

  1. #1

    Default Does this light need a protected battery?

    http://www.xtar.cc/products_detail/&productId=150.html

    Why or why not? Could I just use an unprotected IMR?

  2. #2
    ven's Avatar
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    Default Re: Does this light need a protected battery?

    The only thing stopping lights using unprotected is length usually. The PCB can add a few mm in length, some lights it makes the difference of contact or not!

    Most of mine are unprotected , manufacturers do recommend protected cells in some lights for safety reasons. Most buyers are not Flashaholics , just general users who donít know much about the details. So providing it can make contact with a shorter cell, the user knows about min/max voltages and the safety side. There is no reason not to use unprotected if you wish. Ideally you would want the light to have LVP(low voltage protection) . Other than that, you would need to get a feel for the light and where your at with X amount of use and X voltage used. I generally top up after use, I donít like starting a day(or night) on 1/2 charge cells.

    Another factor would be button or flat top, some lights have physical protection on the positive terminal. By this, basically button tops will only work.

    Protected cell maybe 70mm long, INR maybe 66mm. 4mm is quite a lot, providing good contact springs are used in the light, or cell flexibility may be limited.

  3. #3
    Flashaholic*
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    Default Re: Does this light need a protected battery?

    Yeah, if you're new to 18650's, maybe it's best to use protected cells. Otherwise, unprotected cells are a correct size, can deliver more current, and are cheaper.

  4. #4

    Default Re: Does this light need a protected battery?

    I'm an experienced user and have been making the switch over to nonprotected for most of my lights.

    I don't think this XTAR light has a low voltage cutoff though, which is what concerns me. Unprotected cells make the light run MUCH cooler though, which is why I'm tempted to use them.

  5. #5

    Default Re: Does this light need a protected battery?

    If it doesn't advertise low voltage protection, you should assume it does not have that feature, so a protected cell is recommended.

  6. #6

    Default Re: Does this light need a protected battery?

    Quote Originally Posted by iamlucky13 View Post
    If it doesn't advertise low voltage protection, you should assume it does not have that feature, so a protected cell is recommended.
    Without low voltage protection will it run an unprotected cell down to a dangerous level where it then explodes? Or is this only a possibility?

  7. #7
    ven's Avatar
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    Default Re: Does this light need a protected battery?

    You would know before the voltage dropped bellow 2.5v for example. More than likely it would not even switch on bellow 3v. Also you wonít get high or even medium levels when the voltage is low. Risks are more when left on a low mode for a long duration. If caught quick, most cells can be recovered with little lasting effect(or what can be seen anyway). In between use lock out by undoing tail cap(prevents any parasitic drain and accidental activation).

    Direct shorts are usually when problems start, not by running a cell too low. Charging up after running low,there are risks, but not just draining down.

    Cells are generally quite hardy, but require treating with respect. Keeping an eye on voltage ,IR if can measure, all will give the user time to know if things are going untoward. Recycle and fresh cells would then be a good option. Good cells are cheap, really is no reason to take risks . Good cells are important, just as important is a good charger.


    Using unprotected cells wont make a light run cooler(certainly not noticeably ). On higher demanding lights(direct drive especially), high drains will give better performance (output)with less voltage sag. Higher output =more heat (protected V high drain). Driver dependent(regulated for example or not).
    Last edited by ven; 05-23-2018 at 12:49 AM.

  8. #8
    Flashaholic*
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    Default Re: Does this light need a protected battery?

    Yes, I wouldn't worry about low-voltage-protection unless you're using a light with multiple cells in series, or you're using a light with a boost driver.

    Most single 18650 lights just have a linear regulator or something like that to drop voltage to the emitter if the battery is full. Once the battery gets down to about 3.0v, the voltage is too low for the emitter to do anything more than low modes. It will probably continue to run in that state for at least an hour, probably longer. You'll have plenty of warning the shut off the light. Just make sure to shut off the light, and don't leave it like that. Even if it shuts off by itself because the battery is too low, the battery is still likely powering the driver and draining current.

    For 18650 lights that have a boost driver (such as Zebralight), I've never had one that doesn't have low-voltage-protection, so you're probably safe there too.

    That said, I don't know why all cheap lights don't have LVP, even if they otherwise give a lot of warning. Seems like a simple and inexpensive feature to add.

    Some will say to throw out your cell if you drain it below 2.5v. That's very conservative. Personally, I'd be okay to use one even if it dropped all the way to 1.0v, as long as it didn't stay there long (i.e., days). Still, it's better to be safe, so 2.5v may be a good cut-off.

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