Button Cell Octopus

Introduction: Button Cell Octopus

The Button Cell Octopus replaces button batteries.
This is useful when a replacement battery is not at hand.
It was used to run a thermometer and a humidity gauge from a 4 cents battery. Making this battery is also shown.


Copper sheet (obtained from an Art supplies store)

Connection wire

2 Alligator clips


For the battery:

4 us cents (2 or 4 being post 1982)




Hot glue gun

Soldiering iron


Step 1: Make Connector

Make a connector to replace the button battery with another power source:
- Cut a strip of copper and shape it into a ring the same size as the battery.
- soldier the ring.
- Cut a small circle of copper to act as the top of the battery and to be the negative terminal.
- Soldier hookup wire to the copper ring and small copper disk.

Step 2: Hot Glue It

With the small circle of copper and its attached wire positioned in the center of the outer copper ring, fill with hot glue. This holds everything together and finishes the connector. The wires will either need to come out from the top or a nick will need to be made in the side of the copper ring for them to come out. This depends on the devise the octopus will be inserted into.

Step 3: Testing Connection to Device

Check the connector fits snugly into the devise and connects to its terminals.

Step 4: Add Alligator Clips

Solider Alligator clips to the connector wires.
Make another connector for a different sized button battery and soldier to the same alligator clips to form an octopus.

Step 5: Making a 4 Cents Battery

If no battery is handy, a low amp (2 milliamp) 1.5 volt battery can be made with 4 us cents.

  • 2 coins were made after 1982 - these are made of zinc and copper plated, so file one of the surfaces to expose the zinc.
  • 2 coins were made before 1982 - there are made of copper and will be paired to the zinc ones.
  • Cut 2 disks from cardboard, just slightly larger in diameter than the coins.
  • Soak the cardboard disks in vinegar.
  • Sandwich a cardboard disk between a copper and zinc coin, with the exposed zinc touching the cardboard.
  • Stack the 2 pairs together with the copper made coin being on top of each pair. Connect to the octopus and power the devise. E.g. calculator or thermometer.

If all coins were made after 1982, it will still work but you may need 4 pairs to achieve 1.5 volts. I like how just post 1982 us cent coins can be used either for it's zinc or copper properties and combined together to make electricity.

Step 6: Using the Button Cell Connector

The octopus connector can power devises which use a single button cell battery. I have used it to power:

  • Calculator
  • Thermometer
  • Hygrometer

Step 7: Upping the Volts

Red LED shown, at 4 volts, 2 milli amps.
Next day had dried out Milliamps down to 0.02. Added some more vinegar and wrapped battery holder in cling film. Amps went back to 2.5 Milliamps. Red LED glowed again.

Step 8: Update: Adding Another Leg to the Octopus

Today, I wanted to measure the temperature of some beer and found the food thermometer had been left on and the button battery was flat. As the button battery was a different size to my existing octopus button battery replacements, I made another leg for the octopus and another button battery replacement. Connected it to a 4 cent coin battery. This enabled me to use the food thermometer without a trip to the shops.

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    2 years ago

    Hi Kiselin, Thanks for your comments. The price of a coin battery in Australia is about $2 for a single battery. Buying in bulk is cheaper per battery, though you then have batteries you may or may not need. The original idea for the 'button cell octopus' was so a 'potato battery' could be used to power something useful:
    I also realised it would be useful if a replacement button battery was not at hand and the shops were shut for the day. This happened to me recently:
    The danger from coin batteries is if a small child swallows one, as this can lead to serious internal burns in as little as two hours. Even resulting in the child dying. So keep them well away from infants. Thanks again for your interest and feedback.


    2 years ago

    Gee.. It just happened that this the same day I read your Instr' I just bought a bunch of them coin battery's (CR2016, CR2025...LR44 etc.) say: 12pcs, cost: 12,00€.
    That makes about 1,00€/pcs. Yet, here in Finland the cost of that stuff is more about like 5x the price elsewere in the world,
    So, out there a coin battery cost you about ~0,20€ /each.
    I also had on my list to bye a battery to my thermometer,
    they didn't have just the 1 I needed.
    But to measure my body-temperatury with a thermometer, I guess I wouldn't like to hook up my thermoter into a "extern" power-supply... with them leads dingeling around me, No, I prefer to bye a fresh battery and put it into my thermometer.

    (You can't recycle "ewerything" and save the world, e.g.: Lithium is a wery common metal out there in the universum, there's trillions of tons just in the neibourghity of us).
    The thought, howewer is right. You'll never know what a simple idea can benefit us.
    An in UK. parliament member said:
    " What in the world do we need these steam- and petrol- engines for?
    We do have them bloody horses to do that hard work".
    Google it, it's true.