Transcript BATTERY BASICS - Robotics Academy

BATTERY BASICS
The Lemon Cell (Battery)
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
BATTERY BASICS
INTRODUCTION
• 1800 – Alessandro Volta
discovered the chemical battery by
creating a portable electricity
source known as a “Voltaic Pile”.
• A Voltaic Pile is a device using
pieces of silver and zinc separated
by moist cloth soaked in an
electrolyte (in Volta’s case, sea
water) solution.
• Humphry Davy later proved that
the electricity from voltaic piles
was caused by the chemical
reaction, and not the different
metals, as first assumed.
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BATTERY BASICS
Voltaic Pile
• In the lemon experiment, the
lemon juice allows the metal
plates to gain or lose
electrons. Then, those
electrons travel over to the
other plate (via the electrolyte
solution, lemon juice), forming
a redox reaction.
• The electrolyte is electrically
the same on both sides, but
the reaction creates a
different electrical potential on
the two different plates, so
connecting them shows a
voltage difference.
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The Lemon Battery
Material List
• Figure 1: Alligator
clips with wires
attached.
• Figure 2: Copper and
Zinc metal strips
(Galvanized Sheet
Steel will work fine for
the Zinc strips)
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The Lemon Cell (Battery)
Material List
• Figure 3: A sharp knife
and extra fine steel
wool or Scott’s Brite
• Figure 4:Galvanometer
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The Lemon Cell (Battery)
Material List
• Figure 5: Multi-Meter
• Figure 6: LED’s
(1.8 volt)
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The Lemon Cell (Battery)
Material List
• Figure 7:
Thermometer
with LCD Digital
Display
• Figure 8: DC
Motors and
computer fans.
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The Lemon Cell (Battery)
Material List
• Figure 9:
Lemons
• Figure 10: Egg
Crate to hold
lemons
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The Lemon Cell (Battery)
Assembly Procedures
• Step 1: Obtain a
Copper and Zinc
Strip and clean
both sides with
steel wool or
Scott’s Brite
• Step 2: Obtain a
Lemon, and roll it
on the bench top
to break internal
fibers in the
Lemon.
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The Lemon Cell (Battery)
Assembly Procedures
• Step 3: Using a sharp
knife, make two slits on
one end of the lemon, as
SAFETY
shown.
• Be careful not to cut
yourself!
• Step 4: Insert a copper
strip into one of the slits
and a zinc strip into the
other, as shown. Use an
egg crate to hold the
lemons.
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The Lemon Cell (Battery)
Experiment Procedures
• Step 1: Connect the
alligator clips with wires to
the metal strips, as
shown.
• Step 2: Connect the wires
to the galvanometer on
the Go terminal. Note that
the needle is pegged.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
The Lemon Cell (Battery)
Experiment Procedures
• Step 3: Connect the
lemon to the G1
terminal of the
galvanometer. The G1
terminal has a resistor
inline. What happened?
Why?
• Step 4: Now connect
the lemon to the multimeter with the range set
at DCV 2. How much
voltage is the lemon cell
producing?
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The Lemon Cell (Battery)
Experiment Procedures
• Step 5: Put 3 lemon
cells in series. Why in
series? Note copper is
connected to zinc.
Why? Connect as
shown. Now we have
a lemon battery. Why?
• Step 6: Connect this
Lemon battery to the
multi-meter that is set
to DCV 20. Why DCV
20 and not DCV2?
How much voltage is
the battery producing?
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The Lemon Cell (Battery)
1.8 Volt LED Lemon Powered
• Figure 1: LED Off
• Figure 2: LED On. Using 5
Lemons. What is the voltage of
the Lemons? What is the
amperage of the 5 Lemons?
What is the minimum number
of Lemons that will Power the
LED? What is the voltage of
the minimum number? What is
the amperage?
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The Lemon Cell (Battery)
Powers 3Volt Digital Electric Thermometer
• Figure 1: Thermometer
unplugged. What is the
voltage of the 4 lemons?
What is the amperage?
• Figure 2: Thermometer
on. What is the minimum
number of lemons
needed to power the
thermometer? What is
the voltage and
amperage of this
minimum number?
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The Lemon Cell (Battery)
Can the Lemons power a computer fan?
• How many lemons
will be needed to
power a 12 VDC
computer fan? Will
this be possible?
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