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How to Make homemade batteries... — Parallax Forums

How to Make homemade batteries...

Jorge PJorge P Posts: 385
edited 2011-05-31 19:46 in Robotics
This is a simple build for those of you that don't know how to do it. Parts you will need.
  • About 7 copper coins (pennies)
  • the same amount of nickle or silver coins (nickles or dimes)
  • A paper towel
  • Vinegar or another electrolyte
I am using nickles and pennies. The pennies and nickles will be stacked like so:
  • Penny, paper towel, nickle, paper towel, and repeat using all 10 coins
so I cut 3/4 inch squares out of the paper towel. It is important that the two metals don't touch each other, and also the paper towel pieces shouldn't touch each other either.

One end of the stack should start with a penny and the other end should end with a nickle. Before I started, I soldered a wire to a penny and one to a nickle for the end pieces. It makes it easier to measure the voltage after applying the vinegar to the paper towel pieces.

I used tape to hold it together, and applied the vinegar after it was stacked, In the picture, you can see that it generates 172.8 milivolts. If I were to apply the vinegar to the paper towel first, and then stack them it would generate a bit more voltage, closer to 1 volt, but the smell gets to me. It also helps if the coins are fairly new/shiny.
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Comments

  • HumanoidoHumanoido Posts: 5,770
    edited 2011-05-22 11:18
    Very good experiment!
  • Jorge PJorge P Posts: 385
    edited 2011-05-24 09:03
    Humanoido wrote: »
    Very good experiment!
    Thanks Humanoido, I did all of the "Forrest Mimms III" experiments from his notebooks and mini notebooks that were available at radio shack back in the 80's. His getting started in electronics book also shows how to make a capacitor and resistor from scratch.

    I guess I should note that you should disassemble the battery and wash it off with water when your finished. My batteries corroded after about 16 hours.
  • Dave HeinDave Hein Posts: 6,347
    edited 2011-05-24 09:35
    Jorge, nice experiment. It's fun to build functional things out of common items. I "helped" my son with a science fair project where he powered a digital clock off of a lemon battery. I think it took 2 or 3 lemon cells in series to produce the minimum voltage that the clock needed. I'll have to see if I can find the report he did on that project. BTW, U.S. pennies minted during the past few decades are made of copper-plated zinc. You can sand off the copper plating to reveal the zinc below the plating. I think you will get a higher volatage and current using sanded zinc pennies versus copper-plated pennies.
  • jazzedjazzed Posts: 11,803
    edited 2011-05-25 17:05
    Dave Hein wrote: »
    I "helped" my son with a science fair project where he powered a digital clock off of a lemon battery. I think it took 2 or 3 lemon cells in series to produce the minimum voltage that the clock needed. I'll have to see if I can find the report he did on that project.
    Funny you mention lemons. Just before UPEW I experimented with 1 lemon, 20 gauge untinned solid copper wire, and solid steel bailing wire. I measured 0.9VDC and about 1mA. Under a small load the voltage dropped to about 0.5VDC. Didn't try any in lemons in series because the current was so low. If you could find the report, I would like to read it. ... wonder what would happen if coins were plugged into the lemon.
  • Jorge PJorge P Posts: 385
    edited 2011-05-25 17:45
    jazzed wrote: »
    wonder what would happen if coins were plugged into the lemon.
    If you do the coin battery, you will notice some electrolisys, the copper of the pennies tends to build up on the nickles. If there is more current/voltage from the lemons going into the batteries maybe it will make lemon scented coins.

    What I really think would happen is that the nickle would end up on the pennies.
  • Dave HeinDave Hein Posts: 6,347
    edited 2011-05-26 07:56
    The attached document was used for my son's science fair display board. We found that zinc worked well when paired with copper, silver or carbon. A zinc-carbon cell actually produced the opposite polarity of a zinc-copper or zinc-silver cell. They all produced about one volt using either lemon juice or vinegar -- I believe they both contain acetic acid. It took two lemon cells in series to run the digital clock, which normally used a 1.5 volt alkaline battery.

    We used a galvanized nail for the zinc electrode. A galvanized nail is a steel or iron nail coated with zinc. I believe the carbon electrode was a piece of pencil lead. For the lemon battery, we just stuck the zinc and copper electrodes in the lemon. A potato actually works slightly better than a lemon, and a banana or onion perform about the same as a lemon. The details are in the attached document.

    Dave
    doc
    doc
    Batteries.doc
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  • jazzedjazzed Posts: 11,803
    edited 2011-05-30 23:32
    Dave Hein wrote: »
    The details are in the attached document.
    Nice report. I had about 2mA with 2" wires also.
    Guess I'll have to try powering my propeller module with 2 or 3 lemons in series.

    Cheers.
  • Heater.Heater. Posts: 21,230
    edited 2011-05-31 04:58
    The worrying thing is that I did this experiment in the early 70s using copper, zinc and only the water coming out of the tap in the kitchen. I was surprised to find I could measure a voltage at all with that, can't remember how much now. More surprising is that the thing generated enough power to turn a micro-motor that I had at the time. I shudder to think what was in the water back home in the south of England then!
  • jazzedjazzed Posts: 11,803
    edited 2011-05-31 19:46
    Heater. wrote: »
    The worrying thing is that I did this experiment in the early 70s using copper, zinc and only the water coming out of the tap in the kitchen ....
    Interesting. Would chlorine qualify as an electrolyte? Maybe sulfur? I've had some really bad tap water :p
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