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1.4

Minor Versionm

by Suchitha Vishwa

Introduction

Variant of "DIY Battery", using magnesium electrodes instead of iron nails.

    • Scissors have functional sharp edges. Contact may result in injury. Always keep blades away from fingers and body. Handle with care.

    • Magnesium is an active metal, people with sensitive skin should avoid direct skin contact.

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  1. Using the square of sandpaper, scrape away the oxide layer on both sides of the magnesium strip. Just remove the top layer till the strip is shiny silver instead of dull grey.
    • Using the square of sandpaper, scrape away the oxide layer on both sides of the magnesium strip. Just remove the top layer till the strip is shiny silver instead of dull grey.

    • If using enamelled (insulated) copper wire, scrape off the enamel coating on all of the copper wire.

    • Now cut the wire and the strip in half.

      • You will end up with two 5 cm strips of magnesium. These will serve as the cathode (negative) of the finished cell.

      • Two 25cm lengths of bare copper wire. These will be the anode (positive) of our complete cell.

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    • Using the scissors, cut two rectangular pieces from cloth bag or paper. These pieces should be 3.5 cm X 7cm each.

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    • Now place one of the magnesium strips on one of the shorter sides of the rectangle.

      • Take care that there is at least 1.5 cm of the strip sticking out from the rectangle, this will serve as a negative contact point later.

    • Roll the strip tightly along the rectangular piece to make a cylindrical shape.

    • Hold the bottom of the cylinder to keep it from unravelling.

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    • Now with the cell orientated strip-side up, start winding one of the copper wires on the cell. Make sure that the magnesium and copper are not making contact with each other at any point along the cell.

      • Wind from top to bottom and in the same direction as you wound the cloth serperator. Leave around 2-3cm free at the top before winding. This will serve as a positive contact point.

    • The cell is now almost complete and ready to accept the electrolyte.

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    • Take a paper cup and fill it with an electrolyte of your choice. It's lemon juice in our case but you can use a variety of common acids. Vinegar, carbonated drinks and tamarind juice are good substitutes.

    • Dip the cell in the acid for about 30 seconds. Make sure the serperator has absorbed the liquid.

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    • Now slide the completed cell into the straw with only the free terminals outside.

    • Cut the straw off at the point where the cell ends at the bottom to make one completed cell.

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    • Now make another cell with the steps mentioned previously

    • Attach the positive (copper wire) of one cell to the negative (magnesium strip) terminal of the other. Leaving you with one pair of free terminals to connect the LED to. These will be the positive and negative of the battery.

      • Note that the magnesium strip oxidises fairly quickly so it's necessary to tie the copper and connecting wire to it securely. Sanding the exposed magnesium strip before wiring the cells together will also help in solving this problem.

      • Our average cell voltage with this cell chemistry is 1.2 volts so we need at least two in series to deliver 2.4 volts , which is comfortably above our red LED's switch-on voltage. (2.1 volts)

    • Now with the connecting wires, connect the positive of the battery to the positive of the LED (longer leg) and the negative of the battery to the negative of the LED (shorter leg)

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    • The LED should now be illuminated.

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    • If the LED does not glow, it could be caused by either an improper connection between the cells or a short (positive and negative of the same cell are touching) on one of the cells.

    • Insufficient absorption of the electrolyte by separator.

    • Electrolyte not acidic enough.

    • Electrolyte has dried up.

    • If LED is blue or white, it may need more cells connected in series as these have a higher turning-on potential

    • Magnesium or insulated copper wire not scraped adequately.

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Finish Line

Kailash NR

Member since: 05/02/2017

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