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Thread: Lithium Batteries & LEDs

  1. #1
    Flashaholic*
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    Default Lithium Batteries & LEDs

    When people talk about putting Lithium AAs in lights like the EternaLite, which ones do you mean? I note that Energizer is selling 1.5V Lithium AAs, which normally work out to be $12-$14ish for a 4-battery pack. Helios sells a 3.6V AA which is 3.6V, and around $8 per battery.

    I have a hard time believing people are putting $24 worth of Helios batteries, total of 10.V in their EternaLites. Uh, right? I think Nichias are overdrive at >1.5V per LED.

    Yes yes, I know, I'm stupid, just wanted to make sure.

    Joe

  2. #2

    Default Re: Lithium Batteries & LEDs

    It's the Energizers.

  3. #3
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    Default Re: Lithium Batteries & LEDs

    The Lithium AA is only made by Eveready (patent), hence the higher price. They are also 1.83 VDC before load, each, not 1.5 VDC. Lower internal resistance, plus the higher voltage, can be dicey. I have a pair of 3 nichia LED PR base bulbs that are supposed to be for 3 volts. They barely light on 2 Alkalines of ANY size, are bright on 2 Lithium AAs (3.66 VDC), and overheat fast on 3 alkaline (4.5 VDC). Conversely, the Versalux PR-2 cannot be used with Lithium AAs, as it will overheat very fast.

    Eternalights are regulated to some extent, and the circuit allows for use with Lithium AAs.

  4. #4
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    Default Re: Lithium Batteries & LEDs

    When working with LEDs, do not measure the voltage - measure the current; as each type of LED and even lots have different operating voltage

    LEDs are semiconductor devices, and do not have a linear Power Factor (Voltage/Current) as a resistor does

    A lot of companies are producing LED flashlights using NiChia 5mm LEDs and running them above their maximum rated current

    Although this might not be a problem for the short term; the device is being damaged and eventually will fail; when in doubt what is happening when you try a new battery solution; measure the CURRENT across the device, not the voltage

  5. #5
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    Default Re: Lithium Batteries & LEDs

    Generally speaking, those 3.6V lithium cells in standard formats (AA, C, D) are meant for use as a volatile-memory (such as RAM) back-up power source. You need to check how much current they are designed to deliver. Most will only sustain a constant 20mA.

    If you should find any that are rated to deliver a greater constant current, post it on the forums. Many people will be interested.

    And Joe: We are flashoholics here. Some blokes spend hundreds of dollars on flashlights! [img]images/icons/smile.gif[/img] Of course we'd want the best for our lights. I guess it's the same thing with knife knuts (if you're the same Joe Talmadge from Bladeforums you might understand). Why would anyone spend hundreds of dollars on the Apex Pro if a $30 benchstone could sharpen the knife? [img]images/icons/smile.gif[/img]

  6. #6
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    Default Re: Lithium Batteries & LEDs

    Steelwolf, I just checked the energizer website and it says that their lithium AA's have a max discharge at 2A continuous.
    If you want to check out the pdf, the link is below.

    http://data.energizer.com/datasheets...ithium/l91.pdf

    Regards

    Dale

  7. #7
    *Flashaholic* B@rt's Avatar
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    Default Re: Lithium Batteries & LEDs

    Welcome to CPF Dale!
    You are right about the Energizers, but notice that this is the 1.5V version... [img]graemlins/winkie.GIF[/img]
    Steelwolf is talking about the 3.6V version, like the
    Tadiran 3.6V Lithium AA battery .

    Hope this helps,

  8. #8
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    Default Re: Lithium Batteries & LEDs

    I have a CCrane 3-LED light that works off a single AA lithium battery. I stuck an energizer lithium into it and it wouldn't light up. I scratched my head -- the directions said use lithium AAs, after all -- and then it dawned on me that there was another AA lithium out there. After all, how could a single 1.5V (or rather, 1.8V) battery drive 3 Nichias? Sure enough, I dug up my old discarded battery and found out there's a 3.6V AA. I think the price of that battery is only a couple dollars less than what I paid for the light itself, but there it is. I pretty much "knew" that couldn't be the battery people were putting in Eternalites, but wanted to make sure I wasn't crazy.

    Steelwolf: Ya, that's me, the guy from bladeforums. Of course, here, I'm asking questions that are the equivalent of, "what is the best survival knife, is it the rambo II in 420J".

    Joe

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