LEMON POWER Battery

Lemon Battery

Creating a battery from a lemon is a common project in many

science text books.Successfully creating one of these devices is

not easy.

Batteries consist of two different metals suspended in an acidic

solution.Copper and Zinc work well as the metals and the citric

acid content of a lemon will provide the acidic solution.

Batteries like this will not be able to run a motor or energize

most light bulbs. It is possible to produce a dim glow from an

LED.

The picture at the top of this page shows a basic lemon battery,

a lemon, copper penny and zinc coated nail.

The lemon:A large, fresh,"juicy" lemon works best.

The nail: Galvanized nails are coated in zinc. I used a 2"

galvanized common nail.

The penny: Any copper coin will work. (Canadian pennies

from 1960 - 2001 all worked)

Creating the battery : Insert a penny into a cut on one side of

the lemon. Push a galvanized nail into the other side of the

lemon.

The nail and penny must not touch.

This is a single cell of a battery. The zinc nail and the copper

penny are called electrodes. The lemon juice is called

electrolyte.

All batteries have a " +" and "-" terminal.Electric current

is a flow of atomic particles called electrons.Certain

materials , called conductors, allow electrons to flow

through them. Most metals (copper, iron) are good

conductors of electricity. Electrons will flow from the "-"

electrode of a battery, through a conductor, towards the

"+" electrode of a battery. Volts (voltage) is a measure of

the force moving the electrons. (High voltage is

dangerous!)

I have connected a volt meter to our single cell lemon battery.

The meter tells us this lemon battery is creating a voltage of

0.906 volts.

Unfortunately this battery will not produce enough current

(flowing electrons) to light a bulb.

To solve this problem we can combine battery cells to create

higher voltages. Building more lemon batteries and connecting

them with a metal wire from "+" to "-" adds the voltage from

each cell.

The two lemon batteries above, combine to produce a voltage of

1.788 volts. This combination still does not create enough

current to light a small bulb. Note the red wire connecting the

batteries is joined from "+" (penny) to "-" (galvanized nail).

Four lemon batteries create a voltage of 3.50 volts. We should

be able to light up a small device like an LED (Light Emitting

Diode).

Note the connecting wires go from "+" to "-" on each battery.

LED

To turn on an LED you must determine the "+" and "-"

connections. If you look closely at the red plastic base of an

LED you will notice a "flat" spot (indicated by arrow above).

The wire that comes out beside the flat spot must connect to the

"-" side of a battery, the other wire to the "+" side.

Important information about LEDs : LEDs are designed to

work at very low voltages (~ 2V) and low currents. They will

be damaged if connected to batteries rated at over 2 volts.

LEDs require resistors to control current when used with

batteries rated at over 2 volts. Lemon batteries produce low

current. It is OK to connect an LED to a lemon battery.

In the above image, electrons flow from the "-" (nail) end of our

lemon battery through the LED (making it glow) then back to

the "+" (penny) end of the battery. This is an electronic circuit.

The LED glows dimly with this configuration.

Improving your battery.

The quality of the copper and zinc can be a problem for a

battery like this. Pennies in particular are rarely pure copper.

Try substituting a length of 14 gauge copper wire (common

house wire) for the penny. Experiment with different lengths

and configurations of electrodes. Other sources of zinc and

copper may be found in the plumbing supply department of a

hardware store.

The first battery was created in 1799 by Alessandro Volta .

Today batteries provide the power for an amazing variety of

devices, everything from flashlights to robots, computers,

satellites and cars. Inventors and researchers continue to

improve the battery, designing batteries that last longer and that

are more friendly to our environment.

Understanding how batteries actually work requires a knowledge

of chemistry. The most important factor in battery design is the

electrical relationship between the two metals used in the

battery. Some metals give electrons away while other metals

accept extra electrons. Chemists have investigated metals and

created an "electric potential" table comparing different metals.