This is the famous Lemon Battery, let us make one.
We know that a battery can be created by suspending two different metals in an acid. Lemons, contains citric acid. If we insert a galvanized nail coated in zinc into the one side of our lemon, then make a slit and insert a copper penny on the other side, we should have a battery.
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The volt meter confirms that our two metals; zinc and copper, suspended in the lemon citric acid, create a measurable voltage. In this case, just over one volt, the red lead from the meter connects to the plus side of the battery, the black lead to the minus side. Reversing the lead, we see a minus sign on the meter. Meaning I have the lead’s connected backwards. The copper penny is the plus terminal of this battery.
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Let us connect the LED to this lemon battery. LED is our special type of low voltage, low current device; they can easily be damage by high current. The letters represent the three words; Light Emitting Diode. The word diode alerts us to something special about LED’s. Unlike ordinary light bulbs, LED’s must be connected in a certain way. One lead or wire connects to the plus side of the battery, and the other to the minus side.
A flat spotted at the base, indicates the minus lead. This lead is connected to the minus terminal of the battery. Electrons flow in on the minus lead and out in the plus lead. Connect the LED backwards and it would not work.
I am using small jumper cables with alligator clips, to connect the LED to our lemon battery. We know that the coppers, the plus terminal of our battery, and the zinc coated nail is minus. Our LED is connected properly, but it is not glowing. We do not have enough current flowing to light this LED.
Higher voltage will move more current through the LED, that increases the voltage by adding another lemon to our circuit. Connecting batteries in series, adds the voltage from each battery, remember to connect the plus from one battery to the minus of the other.
Two lemons create over one decimal eight volts, but our LED is still not glowing. We still do not have enough current to light the LED. Let us add two more lemons.
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Now we have over three decimal five volts.
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Connecting our LED, I can now detect the very tiny glow.
Dimming the room lights and looking closely, we can see our LED is glowing. Four lemons create enough voltage and current to create a very dim glow.
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LED’s are available in different colors and sizes. This is a clear high intensity LED, when connected to our lemon battery, a dim red glow is visible.
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Lemon batteries are unable to create the large currents that are needed to operate most electric devices. The low current devices like this calculator are easily operated with two lemons. Review the –battery video for instructions on connecting a calculator.
If you would like to connect larger numbers of lemon batteries, you can actually cut the lemons into quarters, or smaller, and each piece will work as a separate battery cell. When doing this, be careful when cutting, and make sure tat the area between each lemon piece is dry. If the pieces are joined by spilt lemon juice, it will affect the output of the battery.
More information about lemon batteries can be found at our website hilaroad.com follows the projects link.
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