Lemon Batteries
Did you know that some of the fruits and vegetables you eat could also help you
make electricity? Try this and see!
Tools and Materials
- 3 lemons (limes will do)
- 3 shiny copper coins. We used US pennies
- 3 zinc plated screws
- 4 wires, preferably with alligator clips on the ends.
- a small knife
- small paper sticky labels
- a light emitting diode (LED) with a low voltage rating. We used part 276-330 from
Radio Shack.
- a plastic 35mm film canister or similar small container. Use an opaque one,
preferable black, not one made of clear plastic.
- a nail or small awl
- The zinc-plated screws can be found at most hardware stores. They are also called
“galvanized” screws. The zinc plating, which is there to prevent rusting of the steel
screw, gives them a shiny look. The wires with clips can be found at hardware stores
or at electronics suppliers.
What To Do
First, roll all of the lemons, one at a time. Press down with your hand and roll until
you feel the lemon become sort of “squishy.” The purpose of this is to release the
juice inside the lemon. This step is very important; it helps you get the maximum
response from your lemons.
Push and then twist a zinc-plated screw into one of the lemons about 1/3 of the way
from one end. With the knife, carefully cut a 1 cm (3/4 in) slit into the lemon about 1/3
of the way from the other end.
CAUTION: It might be better for an adult to handle the knife. In all cases, please work
with the knife SLOWLY and CAREFULLY.
Insert a copper coin into the slit so that about half of the coin is inside the lemon.
Note: Make sure you use a shiny new coin for this. If it is old and dull, polish it with
steel wool.
Believe it or not, you can now get electricity from the lemon!! It behaves like an electric
cell, with the coin as the positive (+) terminal and the screw as the negative (-)
terminal. Unfortunately, it is a very weak cell. But if you have a couple more, you can
join them to make a lemon battery.
Add coins and screws to the other two lemons the same way you did with the first.
Then, with the wires and clips, join the three lemon cells together, so that the screw
of the first lemon is connected to the coin of the second lemon, and so on. Add wires
and clips to the first coin and the last screw also.
Finally, label the clip from the first coin with a “+” and the clip from the last screw with
a “- “. Like a real battery, your lemon battery has a positive (+) terminal and a negative
(-) terminal.
When connected like this in what is called a series connection, the lemons work
together to create about the same voltage, or electrical force, as a couple of small
flashlight batteries, somewhere between 2.5 and 3 volts. But this lemon battery does
not create enough electrical current to light a flashlight bulb.
How can we tell if we really have created a battery? One way is to connect it to an
electronic device that needs no more than about 2.5 to 3 volts but that does not
require much electrical current. One such device called a light emitting diode, or LED
for short. A low voltage and small current can cause an LED to light up.
The specifications on our LED package are: 5mm Red LED, 1.8 volt, 20mA. This
means the diameter of the LED is 5 mm, and that it requires 1.8 volts and 20
milliamps of current to light up. Actually, the LED will light up dimly with less than 20
milliamps. Our lemon battery has enough volts but not nearly enough milliamps. So
we will have to find a way to see its dim light. We tried enclosing it in a film canister to
shield it from outside light.
With the nail, CAREFULLY punch two holes in the sides of the film canister, about
halfway down. You might want to get an adult to do this for you.
Next, mark one hole with a “+” label and the other with a “-“ label.
Bend the wires of the LED into smooth outward curves. Then observe the LED
closely. It is mostly round. However, if you tilt it in a certain way, you will be able to
see a flat surface near one of the wires. The wire nearest this flat surface is the
negative terminal. In the photograph, the wire on the left is the negative terminal of
the LED. Can you see the small flat surface by the leftmost wire?
Line up the negative terminal wire of the LED with the “-“ labeled hole in the film
canister. Insert the LED into the canister. Thread the negative terminal wire of the
LED through the “-“ labeled hole, and the other (positive terminal) wire through the
“+” labeled hole.
Pull the wires through the holes and secure them in place with the labels. Add labels
to the top of the canister as well. Make sure that the LED is facing up.
Let’s get everything prepared for the big moment. Line up the “+” side of the LED
canister with the “+” clip of your lemon battery. Bring the “-“ clip of your lemon battery
close to the “-“ side of the canister.
Now we are ready! Connect the positive terminal of the LED to the positive terminal of
your lemon battery. Connect the negative terminal of the LED to the negative terminal
of your battery. The LED lights up!!
The LED is very dim, due to the small electrical current from your battery. The dark
canister helps you to see this dim light. The end of the LED acts like a magnifying
glass. When you look directly into the end of the LED, you can see the light easily.
This proves that you really have made a lemon battery that works!! Congratulations!!
Troubleshooting
If you can’t see the LED light up try these fixes:
You may have the polarity of the LED reversed, that is, the + and - switched. Reverse
the LED and see if it lights up.
The LED may be very dim. Dry it in a darker room and let you eyes adjust to the
dimmer light before testing.
Make sure all of the connections are secure: wires clipped to the coins and screws
and coins and screws firmly in the lemons.
More Things To Try
Over time, the voltage in your lemon battery will go down. See how long your lemon
battery will last. After a while, you might notice a darkening of a lemon near the
screw. If you remove the screw and insert it (or a new zinc-plated screw) at another
place in the lemon, you can partially restore the strength of your battery. You can also
“juice up” your battery a little bit by moving the pennies in and out of their slots from
time to time.
Try more than three lemons connected together. Is the LED light brighter? Does the
lemon battery last longer?
Try larger pieces of copper and zinc.
Try using an incandescent bulb - the kind used in a flashlight. Can you make a fruit
battery strong enough to light it?
Try other fruits and vegetables, such as potatoes and tomatoes. What about
grapefruit and oranges? Can you think of a way to try bottled lemon juice?
Obtain an electronic instrument called a multimeter. This device allows you to
measure voltage directly. What is the voltage of your lemon battery? What is the
voltage from a single lemon cell?
Credit: http://www.seed.slb.com/en/scictr/lab/fruit/index.htm
Special thanks to William J Beaty "Bill" from Science Hobbyist for correcting our
previous lemon battery experiment and suggesting this one instead.
Science Hobbyist
make electricity? Try this and see!
Tools and Materials
- 3 lemons (limes will do)
- 3 shiny copper coins. We used US pennies
- 3 zinc plated screws
- 4 wires, preferably with alligator clips on the ends.
- a small knife
- small paper sticky labels
- a light emitting diode (LED) with a low voltage rating. We used part 276-330 from
Radio Shack.
- a plastic 35mm film canister or similar small container. Use an opaque one,
preferable black, not one made of clear plastic.
- a nail or small awl
- The zinc-plated screws can be found at most hardware stores. They are also called
“galvanized” screws. The zinc plating, which is there to prevent rusting of the steel
screw, gives them a shiny look. The wires with clips can be found at hardware stores
or at electronics suppliers.
What To Do
First, roll all of the lemons, one at a time. Press down with your hand and roll until
you feel the lemon become sort of “squishy.” The purpose of this is to release the
juice inside the lemon. This step is very important; it helps you get the maximum
response from your lemons.
Push and then twist a zinc-plated screw into one of the lemons about 1/3 of the way
from one end. With the knife, carefully cut a 1 cm (3/4 in) slit into the lemon about 1/3
of the way from the other end.
CAUTION: It might be better for an adult to handle the knife. In all cases, please work
with the knife SLOWLY and CAREFULLY.
Insert a copper coin into the slit so that about half of the coin is inside the lemon.
Note: Make sure you use a shiny new coin for this. If it is old and dull, polish it with
steel wool.
Believe it or not, you can now get electricity from the lemon!! It behaves like an electric
cell, with the coin as the positive (+) terminal and the screw as the negative (-)
terminal. Unfortunately, it is a very weak cell. But if you have a couple more, you can
join them to make a lemon battery.
Add coins and screws to the other two lemons the same way you did with the first.
Then, with the wires and clips, join the three lemon cells together, so that the screw
of the first lemon is connected to the coin of the second lemon, and so on. Add wires
and clips to the first coin and the last screw also.
Finally, label the clip from the first coin with a “+” and the clip from the last screw with
a “- “. Like a real battery, your lemon battery has a positive (+) terminal and a negative
(-) terminal.
When connected like this in what is called a series connection, the lemons work
together to create about the same voltage, or electrical force, as a couple of small
flashlight batteries, somewhere between 2.5 and 3 volts. But this lemon battery does
not create enough electrical current to light a flashlight bulb.
How can we tell if we really have created a battery? One way is to connect it to an
electronic device that needs no more than about 2.5 to 3 volts but that does not
require much electrical current. One such device called a light emitting diode, or LED
for short. A low voltage and small current can cause an LED to light up.
The specifications on our LED package are: 5mm Red LED, 1.8 volt, 20mA. This
means the diameter of the LED is 5 mm, and that it requires 1.8 volts and 20
milliamps of current to light up. Actually, the LED will light up dimly with less than 20
milliamps. Our lemon battery has enough volts but not nearly enough milliamps. So
we will have to find a way to see its dim light. We tried enclosing it in a film canister to
shield it from outside light.
With the nail, CAREFULLY punch two holes in the sides of the film canister, about
halfway down. You might want to get an adult to do this for you.
Next, mark one hole with a “+” label and the other with a “-“ label.
Bend the wires of the LED into smooth outward curves. Then observe the LED
closely. It is mostly round. However, if you tilt it in a certain way, you will be able to
see a flat surface near one of the wires. The wire nearest this flat surface is the
negative terminal. In the photograph, the wire on the left is the negative terminal of
the LED. Can you see the small flat surface by the leftmost wire?
Line up the negative terminal wire of the LED with the “-“ labeled hole in the film
canister. Insert the LED into the canister. Thread the negative terminal wire of the
LED through the “-“ labeled hole, and the other (positive terminal) wire through the
“+” labeled hole.
Pull the wires through the holes and secure them in place with the labels. Add labels
to the top of the canister as well. Make sure that the LED is facing up.
Let’s get everything prepared for the big moment. Line up the “+” side of the LED
canister with the “+” clip of your lemon battery. Bring the “-“ clip of your lemon battery
close to the “-“ side of the canister.
Now we are ready! Connect the positive terminal of the LED to the positive terminal of
your lemon battery. Connect the negative terminal of the LED to the negative terminal
of your battery. The LED lights up!!
The LED is very dim, due to the small electrical current from your battery. The dark
canister helps you to see this dim light. The end of the LED acts like a magnifying
glass. When you look directly into the end of the LED, you can see the light easily.
This proves that you really have made a lemon battery that works!! Congratulations!!
Troubleshooting
If you can’t see the LED light up try these fixes:
You may have the polarity of the LED reversed, that is, the + and - switched. Reverse
the LED and see if it lights up.
The LED may be very dim. Dry it in a darker room and let you eyes adjust to the
dimmer light before testing.
Make sure all of the connections are secure: wires clipped to the coins and screws
and coins and screws firmly in the lemons.
More Things To Try
Over time, the voltage in your lemon battery will go down. See how long your lemon
battery will last. After a while, you might notice a darkening of a lemon near the
screw. If you remove the screw and insert it (or a new zinc-plated screw) at another
place in the lemon, you can partially restore the strength of your battery. You can also
“juice up” your battery a little bit by moving the pennies in and out of their slots from
time to time.
Try more than three lemons connected together. Is the LED light brighter? Does the
lemon battery last longer?
Try larger pieces of copper and zinc.
Try using an incandescent bulb - the kind used in a flashlight. Can you make a fruit
battery strong enough to light it?
Try other fruits and vegetables, such as potatoes and tomatoes. What about
grapefruit and oranges? Can you think of a way to try bottled lemon juice?
Obtain an electronic instrument called a multimeter. This device allows you to
measure voltage directly. What is the voltage of your lemon battery? What is the
voltage from a single lemon cell?
Credit: http://www.seed.slb.com/en/scictr/lab/fruit/index.htm
Special thanks to William J Beaty "Bill" from Science Hobbyist for correcting our
previous lemon battery experiment and suggesting this one instead.
Science Hobbyist
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