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Thread: CR2 Lithium Battery

  1. #1
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    Default CR2 Lithium Battery

    Hello,

    I found a bunch of used CR2 lithium batteries at my work place. I took it home and measured it and most are at 2.7-2.8v. Are they still good to use? Dangerous? Thanks.

  2. #2

    Default Re: CR2 Lithium Battery

    Are they lithium primaries or rechargeables?

    Primaries can be run down to nothing, which is what I suspect you have.

    Rechargeables are when it can get a little tricky.

    Out of curiosity, what light are you using them in?

  3. #3
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    Default Re: CR2 Lithium Battery

    I made a spacer, so it can run on my L1. I think it can run on other cr123 lights with that spacer.

    Btw, they are primaries.

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    Default Re: CR2 Lithium Battery

    No, at 2.7v or 2.8v, they're pretty-much dead.

  5. #5
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    Default Re: CR2 Lithium Battery

    Darn. But continue using them will cause no hazzard? Just not as bright as 3.0v?

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    Default Re: CR2 Lithium Battery

    Should be fine, though I'm not sure what would happen if one got reverse-charged in a series application. Your light would probably turn off long before that happened.

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    Default Re: CR2 Lithium Battery

    What brand are they?
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    Default Re: CR2 Lithium Battery

    If you are using them with a spacer in a CR123 light, please be aware of maximum current draw. Only use the light on low modes. Also only use a single cell.

  9. #9

    Default Re: CR2 Lithium Battery

    If you are using that Surefire L1 Gen5 you posted about that has a high mode of 22 lumens, then I think the high mode is safe to use. Duracell Cr2 batteries have a 1000 mAh maximum continuous rating: I'm assuming you are pulling less than 50 mAhs? But I have no idea about using two batteries at a time. Like WalkintotheLight said, if the voltage/capacity is mismatched where one battery has more capacity than the other, you can run into serious problems.

    The name brand of the battery makes a difference and I'm sure you know to inspect the batteries for physical damage too; no tears in the wrapper etc.

  10. #10
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    Default Re: CR2 Lithium Battery

    Yea, I am using it in my L1 gen 5. They are Energizier. I did check for physical damage

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    Default Re: CR2 Lithium Battery

    Quote Originally Posted by dealgrabber2002 View Post
    Yea, I am using it in my L1 gen 5. They are Energizier. I did check for physical damage
    Okay, thanks.

    As Zipplet said, probably okay for light duty, and avoid 2xCR2 configurations, as those can be problematic for old, aging, or otherwise unequal cells.
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  12. #12
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    Default Re: CR2 Lithium Battery

    Didn't know dropping .2-.3v would make the battery almost dead.

  13. #13

    Default Re: CR2 Lithium Battery

    The nominal voltage is 3 but they actually start off somewhere around 3.27

    At 22 lumens, I bet you still get some useful runtime out of them.

  14. #14
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    Default Re: CR2 Lithium Battery

    Quote Originally Posted by LogicalBeard View Post
    At 22 lumens, I bet you still get some useful runtime out of them.
    I would certainly use them for this specific application in that case. Saves a little more from the landfill/recycling!

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    Default Re: CR2 Lithium Battery

    Quote Originally Posted by LogicalBeard View Post
    At 22 lumens, I bet you still get some useful runtime out of them.
    He will probably get about an hour runtime out of them, maybe two, at that output. Not great, but okay. IMO, I'd just use a rechargeable RCR123 in that light, if it can handle 4.2v. It will probably give him 10x the runtime.

  16. #16
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    Default Re: CR2 Lithium Battery

    One of the battery did 7 hrs on low. Still the same brightness from start. Haven't try high yet.

    I use 3.2v lifep04 in my L1. Just found all these batteries with some juice, just want to make them useful.

  17. #17
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    Default Re: CR2 Lithium Battery

    You can take a look at the Energizer CR2 spec sheet, if you like, to get an idea of the voltage curve under continuous load ....

    Just guesstimating based on that, it looks like a ~ 30 mA drain will run ~ 35 hrs total, dropping from ~ 3.1V to 2.8-ish V within first hour, then a further drop from ~ 2.8V to ~ 2.5V over the next 30 hrs.

    Pretty empty past that, with voltage falling from 2.5V to < 1.5V in the next 5 hrs.
    ... is the archimedes peak

  18. #18
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    Default Re: CR2 Lithium Battery

    Quote Originally Posted by archimedes View Post
    You can take a look at the Energizer CR2 spec sheet, if you like, to get an idea of the voltage curve under continuous load ....

    Just guesstimating based on that, it looks like a ~ 30 mA drain will run ~ 35 hrs total, dropping from ~ 3.1V to 2.8-ish V within first hour, then a further drop from ~ 2.8V to ~ 2.5V over the next 30 hrs.

    Pretty empty past that, with voltage falling from 2.5V to < 1.5V in the next 5 hrs.
    That is under load, though. He's measuring the voltage at rest. 2.8v resting is probably pretty close to empty. 90% drained? I dunno, could be more juice left in it that what I'm guessing. Only way is to run a test and see.

  19. #19
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    Default Re: CR2 Lithium Battery

    Yes, measured under load.

    Open circuit voltage is not especially informative for state-of-charge in lithium primaries (due to passivation, among other reasons)
    Last edited by archimedes; 10-07-2018 at 02:24 PM.
    ... is the archimedes peak

  20. #20

    Default Re: CR2 Lithium Battery

    Good point. I have a ZTS battery tester and a Fluke 117 multimeter but I never test under a load with the fluke. How many ohms do you recommend for a load on a CR2?

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    Default Re: CR2 Lithium Battery

    Quote Originally Posted by LogicalBeard View Post
    Good point. I have a ZTS battery tester and a Fluke 117 multimeter but I never test under a load with the fluke. How many ohms do you recommend for a load on a CR2?
    I have the ZTS too. It boasts a pulsed load test, which I assume is the “gold standard.” At over $100 for the unit, it’ll be awhile before I recoup the initial investment, but I luv it as I can get more accurate readings of state of charge now for 40 different batteries.
    Last edited by magellan; 10-09-2018 at 05:32 PM.
    It is better to buy a beautiful, expensive, custom flashlight than to curse the darkness.

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