Alternatives to coin-cell batteries

Activities Paper Circuits ⚡️
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At least once a year, we ship coin-cell batteries to places like Hawaii or Alaska because it’s not easy to find them locally. It’s not equitable to have an activity where materials are hard to find!

The button LEDs we use require 2.2 to 3.0 volts. Here are alternatives to a 3-volt coin-cell battery:

  • 2 AA batteries + conductive wires
    You can stack 2 AA batteries. They are 1.5 volts each, so you can get 3 volts with 2. Alternatives to conductive wires include: copper tape, chenille stems (pipe cleaners), and aluminum foil. Instructables link inspiration
  • 3 Lemons / potatoes + copper wires (or coins) + zinc screws
    A single lemon is about 0.7 to 1.0 volts. A single potato is about 0.5 to 0.9 volts. Chain up 3 lemons ( or 4 to 6 potatoes) with copper wires (or coins) and zinc (usually a gavanized metal screw) to power an LED. Wikihow link inspiration

I’ll make some examples and take photos soon!

High ceiling:

But what if you only want to use a single AA battery?
(and have access to electronic parts!!)

This can be done with a “joule thief” patented as early as 1930, that uses one AA (1.5 volt) battery + ferrite toroid + wires + resistor + transistor to increase the voltage output of a single battery and can power a 3-volt LED. Wikipedia link | Instructables link | Reddit link with helpful graphic | Youtube video from the person who named the concept “joule thief”

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Bill Nye Science Rules GIF | GIFDB.com

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Okay, finally got around to testing this out:

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C0D0DDE3-00C6-4D55-92E2-9890BB584BC3_4_5005_c360×480 31.4 KB

  • The positive end of the AA battery is the one that has the bump in the center.
  • Do not connect the positive side to the negative side of the battery (with the copper tape) or it’ll start heating up…
  • Taping the batteries together is not straightforward. Even if the two batteries are touching underneath the tape, I needed to put some pressure to squeeze them together, for the LED to light up

As a replacement for the coin cell battery for paper circuits activity, we would need to figure out how to hold the batteries to the paper for a successful connection every time. (Maybe craft little paper box for the battery?)

On the bright side, AA alkaline batteries pack a lot of energy, so the LEDs would be able to stay lit for a long time!

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That is cool, but think I will stick to coin ones, easier :blush:

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Yeah the coin cell batteries are a great fit for paper circuits.

These explorations with other batteries are here to support people who might not easily find and purchase the coin cell batteries. AA batteries can be more accessible, which is why we tried this out!