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Thread: Vampire hunting with a digital multimeter

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    Flashaholic jnj1033's Avatar
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    May 2006
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    Default Vampire hunting with a digital multimeter

    I picked up a digital multimeter from Harbor Freight for use with my new 18650 setup. Once I got the hang of checking battery voltage, I decided to experiment and find out which of my alkaline lights are "battery vampires."

    I put some partly depleted AAA alkaline cells in several of my lights, turned them on, and left them alone for a while. Periodically I switched them off and back on to see how low I could run the voltage before they wouldn't consistently turn on anymore. Once a light started requiring "rest" before switching on again, I measured the cell voltage and moved on to the next light.

    I didn't measure runtime- only voltage.

    Here are some rough numbers. This is not a scientific test- just some observations.

    Dorcy 1AAA LED (brighter version w/ clear lense): Ran a cell down to about .8 volts in this light. Turned it off and back on. Wouldn't light until the cell had rested for a few seconds.

    Fenix E1: Required rest to relight around .4 volts. Very dim at this point.

    Fenix E01: Down to about .3 volts and still running slightly brighter than the E1 at higher voltage. This test is still pending and will continue tonight.

    Lightflux LF2: Not sure where the cutoff is, but definitely won't turn on below 1 volt, even on the lowest (.01 lumen) setting. I assume the microprocessor requires a higher voltage to operate.

    Haven't tested my new LD01 yet.

    Based on the above observations, the E01 seems like a good light to have during an extended power outage or other emergency. It might not be my initial go-to light, but it will produce usable, albeit dim, light long after my other lights have ceased to function on the same cells. It also works well with depleted cells as a nightstand light, because the dim output doesn't dazzle my night-adapted eyes.

    Note: Don't worry- I won't be doing this w/ lithium cells. I'm aware of the safety issues and am not taking any chances.

    Sent from my phone. There are many like it, but this one is mine.

  2. #2

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    Quote Originally Posted by jnj1033 View Post
    Based on the above observations, the E01 seems like a good light to have during an extended power outage or other emergency. It might not be my initial go-to light, but it will produce usable, albeit dim, light long after my other lights have ceased to function on the same cells. It also works well with depleted cells as a nightstand light, because the dim output doesn't dazzle my night-adapted eyes.

    Note: Don't worry- I won't be doing this w/ lithium cells. I'm aware of the safety issues and am not taking any chances.
    Consider a moonlight mode light, like a Preon P0, which will also greatly extend batt life when voltage is still above 1.0.

    And don't do vampire test with Alks on multi-cell lights either - you'll pop them. Don't ask how I know.

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