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Re: Where would I find some zinc? (& homemade battery questions)

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  • Justin Fisher
    ... Yep. Fortunately, by continuous I really mean replace it by hand once a day or so, as needed sort of thing, rather than something like an automated
    Message 1 of 8 , Jan 2, 2001
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      > One thing to consider is that the electrolyte between the electrodes
      > of each cell must be electrically isolated from the other cells or
      > else you will have a short circuit. That makes continuous
      > replentishment of electrolyte for series connected cells a problem.

      Yep. Fortunately, by "continuous" I really mean "replace it by hand
      once a day or so, as needed" sort of thing, rather than something like
      an automated pipe-feed, so it's not a big issue.

      But that's a pretty cool idea - if you were to fix in place your cells
      (open cups) just below a high tide line, the tide would swamp the
      battery twice a day, replacing the water, and when the tide went out
      a little, the cells would be isolated again and you have a
      working replenished battery. (Assuming new electrolyte = new power)

      Put it on the back of a bot that lives on the beach...
      (perhaps use resistance-sensors on the feet/wheels, so that when the
      power gets low, it starts seeking damper ground, and thus finds its
      way to the ocean water...)

      Actually, a solar panel seems FAR easier and more reliable :-), but
      its still an interesting idea for a fixed installation. Regarding the
      toxicity of the old electrolyte, my understanding is that there is
      plenty of zinc in seawater already, but I imagine copper might be a
      bit nastier...
    • harsh@lanl.gov
      ... zinc is also known as pot metal. It s used for all sorts of inexpensive castings; lock bodies, door knobs, etc. Probably if you ask a junk yard, or metal
      Message 2 of 8 , Jan 2, 2001
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        On 02-Jan-2001 Justin wrote:
        > I've thought of a pretty neat whodacky to make, but part of the charm of
        > it is having it powered by a small home-made salt-water battery, for
        > which I need to find some zinc.
        > Any ideas where you can get the stuff? (I presume it's not dangerous -
        > please correct me if I'm wrong :-)


        zinc is also known as pot metal. It's used for all sorts of inexpensive
        castings; lock bodies, door knobs, etc. Probably if you ask a junk yard, or
        metal recycler you could get some fairly cheaply. zinc has the nice property
        that it melts about the same temperature as lead, so you can use a plumber's
        pot to melt it.







        >
        > Now, any ideas where I can get the stuff that DOESN'T involve me ripping
        > up old car batteries and getting acid all over my clothes? :-)
        >
        > On the subject, if anyone can answer any of the following, I'd be very
        > grateful:
        >
        > Will simply replacing the saltwater "replenish" the cell completely?
        > Would the electrodes need cleaning, or can you just keep replacing
        > saltwater until the electrodes are eroded into nothing?
        >
        > My understanding is that a zinc/copper/saltwater cell will generate
        > roughly 0.5V. Assuming the volume is about the same as an AA battery,
        > how much power are you likely to get? (eg a ballpark guess - would it
        > last 1/4 as long as an AA running a low-power application (eg about
        > 8mA)? 1/8th? Any ideas? I lack the zinc to find out :-)
        >
        > Does the surface area of the electrodes make a difference? (I'm guessing
        > it would relate to how much currant you can draw out of the battery)
        >
        > Are saltwater batteries rechargable in any useful sense? :-)
        >
        > To unsubscribe from this group, send an email to:
        > beam-unsubscribe@egroups.com

        ---------------------------------------------
        Jim Harsh E-Mail: harsh@...
        Los Alamos National Laboratory, MS P940
        Los Alamos, NM 87545
        505-665-0485, FAX - 505-665-3359
        Date: 02-Jan-2001,Time: 11:43:24
        ---------------------------------------------
      • dr_soong@beer.com
        I ve seen a lot of interesting commentary, but haven t yet seen a reply to the original request, so here s a bit of help: Any hardware store shoul carry
        Message 3 of 8 , Jan 2, 2001
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          I've seen a lot of interesting commentary, but haven't yet seen a
          reply to the original request, so here's a bit of help:

          Any hardware store shoul carry galvanized metal, which is steel or
          iron which has been coated by zinc. You should be able to buy it in
          sheets, but if not, galvanized nails or bolts are available anywhere.

          They won't last as long as solid zinc, but should do OK for a low
          current draw project.

          Also note that it doesn't HAVE to be zinc/copper. Really any two
          dissimilar metals will provide some type of charge. Play with
          different materials and see what results you get. Also try different
          electrolytes. Acids seem to work best, so try things like lemon juice
          or tomato juice.

          Have fun!

          Dr. Soong
        • Bruce Robinson
          ... Well, the plant just down the hill makes 1/4 million tonnes of higher purity zinc each year. However, they don t sell to the likes of me ... even when I
          Message 4 of 8 , Jan 2, 2001
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            Justin wrote:
            >
            > ... a small home-made salt-water battery, for which I need to
            > find some zinc. Any ideas where you can get the stuff? (I
            > presume it's not dangerous -

            Well, the plant just down the hill makes 1/4 million tonnes of higher
            purity zinc each year. However, they don't sell to the likes of me ...
            even when I worked for them :(

            As was mentioned, zinc is used for making die castings (door handles,
            parts of tools, etc.) Unfortunately, most zinc die casting alloy
            contains a modest amount of aluminum (about 5% or so) to reduce the
            melting temperature and improve flow. I don't know what affect the
            aluminum will have on a battery. BTW, melting temperature of zinc is
            quite a bit higher than that of lead -- 419 Celsius vs 327 C. Die
            casting allow melts at around 380 C.

            Galvanized material was mentioned as a possible source, but the zinc
            layer isn't very thick. You could melt the zinc off with a propane
            torch, but most of it will oxidize, so I doubt that is practical.

            Nowadays fishing weights are often made of zinc instead of lead, but I
            don't know if it's an alloy or not.

            The most readily available source for pure zinc in these parts is from
            roofing companies. Here in Canada, you can buy sheet zinc in long strips
            (10 cm wide or so) to put along the top of your roof. A tiny bit
            dissolves in rainwater and washes down, killing off lichens and fungus.

            Having got you worried about the toxic properties of zinc, it ISN'T
            toxic to humans. You are far more likely to get a toxic dose of zinc
            from taking too many mineral supplements than you are from handling the
            stuff. To put it into perspective, the zinc plant I worked for also
            manufactured lead. EVERY employee had to have an annual blood test for
            lead, and people actually working in the lead plant had to have monthly
            tests. NO ONE had to be tested for zinc, even the people working with it
            every day. Zinc is simply not very toxic, and does not get into the body
            easily in any case.

            I don't have a lot of information on zinc-copper cells in salt water, by
            my electrochemistry tables suggest your 1/2 volt estimate isn't too far
            off. The problem is that a copper-saltwater cell actually reduces the
            voltage. In the early days of electrolytic cell development, a popular
            cell involved a cathode of zinc in sodium chloride solution (1:4
            mixture), and an anode of copper in saturated copper sulphate. Voltage
            was just a tad over 1 volt. However, I don't have any information about
            how these early double cells were connected to each other. Sorry.

            Bruce
          • Chuck Britton
            You ll find a core of zinc inside every (recent) US penny. File or sand one face of copper of and solder onto the other copper face??? Sorry, but it s not the
            Message 5 of 8 , Jan 2, 2001
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              You'll find a core of zinc inside every (recent) US penny. File or
              sand one face of copper of and solder onto the other copper face???


              Sorry, but it's not the electrolyte that you'll have to replace. It's
              the metals. Once they 'corrode away' they gotta be replaced.

              Aluminum cans can also become electrolytic cell 'fuel' but you gotta
              remove the plastic film on the inside of the can.



              At 11:49 AM -0700 1/2/01, harsh@..., you wrote about RE: [beam]
              Where would I find some zinc? (& homemade b:


              >On 02-Jan-2001 Justin wrote:
              > > I've thought of a pretty neat whodacky to make, but part of the charm of
              > > it is having it powered by a small home-made salt-water battery, for
              > > which I need to find some zinc.
              > > Any ideas where you can get the stuff? (I presume it's not dangerous -
              > > please correct me if I'm wrong :-)

              -. .-. .-. .-. .-. .-. .-. .-. .-. .-
              \ / \ / \ N / \ C / \ S / \ S / \ M / \ / \ /
              `-' `-' `-' `-' `-' `-' `-' `-' `-'
              Chuck Britton Education is what is left when
              britton@... you have forgotten everything
              North Carolina School of Science & Math you learned in school.
              (919) 286-3366 x224 Albert Einstein, 1936
            • Chuck Britton
              At 4:50 PM -0800 1/2/01, Bruce Robinson, you wrote about Re: [beam] ... I ve seen chemistry labs where these two half cells were connected by a bridge
              Message 6 of 8 , Jan 2, 2001
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                At 4:50 PM -0800 1/2/01, Bruce Robinson, you wrote about Re: [beam]
                Where would I find some zinc? (& homemade b:

                > In the early days of electrolytic cell development, a popular
                >cell involved a cathode of zinc in sodium chloride solution (1:4
                >mixture), and an anode of copper in saturated copper sulphate. Voltage
                >was just a tad over 1 volt. However, I don't have any information about
                >how these early double cells were connected to each other.


                I've seen chemistry labs where these two 'half cells' were connected
                by a 'bridge' consisting of a glass inverted U tube that was packed
                with a gelatin mix. But it was called a 'salt bridge' so ya better
                check with a chemist.

                I'm considering a 'Voltaic Pile' of US pennies. One surface sanded
                down to the zinc. Lots of 'em stacked up with filter paper moistened
                with salt water between each disk. Dunno if it will work.

                -. .-. .-. .-. .-. .-. .-. .-. .-. .-
                \ / \ / \ N / \ C / \ S / \ S / \ M / \ / \ /
                `-' `-' `-' `-' `-' `-' `-' `-' `-'
                Chuck Britton Education is what is left when
                britton@... you have forgotten everything
                North Carolina School of Science & Math you learned in school.
                (919) 286-3366 x224 Albert Einstein, 1936
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