Unit 1-5

Question 1

What is a battery?

Answer 1

One or more electromechanical cells that convert stored chemical energy into electrical energy

Question 2

What was the first battery?

When was it invented? By who?

Answer 2

Voltaic pile

1799 by Alessandro Volta

Question 3

What is a voltaic cell?

What does each half-cell include?

Answer 3

Two half-cells connected by a conductive electrolyte

One half-cell has electrolyte and the negative electrode while the other has electrolyte and the positive electrode

Question 4

Is the chemical reaction reversible for a primary cell battery?*

When does the chemical reaction start?

Examples?

Answer 4

Chemical reaction cannot be reversed (recharged)

Drain from the moment they are produced, chemical reaction begins right away

Zinc-carbon
Alkaline

Question 5

Is the chemical reaction reversible for a secondary cell battery?*

What must be done before the battery can produce full power?

Answer 5

Chemical reaction can be reversed (recharged)
Designed to be used, recharged, and used again multiple times

Must be charged after assembly to produce full power

Question 6

Which type of battery, primary or secondary, has a higher energy density?*

What is the intended use for primary cells?*

What is the intended use for secondary cells?*

Answer 6

Primary

Low load applications

High-drain applications (hi loads)

Question 7

What type of battery is used in a majority of aircraft?

Larger aircraft?

Answer 7

24-volt lead acid battery (secondary)

Nickel Cadmium (NiCd)

Question 8

What is a wet cell?*

Why is it important that it is vented?

Answer 8

Vented cell
Battery that has a liquid electrolyte (sulfuric acid)
The liquid covers all internal parts, (the electrodes)

Gases are produced during operation must be vented so the gas can escape (vent caps)

Question 9

Are wet cells primary or secondary batteries?*

What are they used in?*

Answer 9

Can be primary or secondary

Aircraft & automotive batteries and in industry for standby power for telecommunication

Question 10

What is a dry cell?*

Answer 10

Electrolyte immobilized as a paste with only enough moisture in the paste to allow current to flow

Question 11

List some differences between wet and dry cells*

Answer 11

Wet cells have a liquid electrolyte, whereas dry cells are filled with a paste
Wet cells will spill if inverted, dry cells will not
Wet cells are vented, whereas dry cells are not

Question 12

Describe the chemistry of a zinc-carbon battery

Answer 12

Anode (negative pole) = Zinc (cylindrical pot)
Cathode (positive pole) = Carbon (central rod)
Electrolyte = ammonium chloride (paste)

Question 13

What is a VRLA battery?*

Answer 13

Valve-regulated lead-acid battery
Low-maintenance
Addition of water
Cannot spill electrolyte if cell is inverted (weighted valve)

Question 14

Describe gel cell technology*

Where are these used?

Answer 14

Recombinant battery
The oxygen created at the positive plates recombines with the hydrogen created at the negative plates
This decreases pressure and prevents water loss

Applications including aircraft, acrobatic aircraft

Question 15

What are lead-acid storage batteries made of?*

What are they found in?

Answer 15

Lead compound plates in a solution of sulfuric acid

Lead acid batteries can be found in smaller aircrafts

Question 16

List advantages and disadvantages of lead-acid batteries*

Answer 16

Advantages:
Less expensive

Disadvantages:
Less power-to-weight ratio
Must be checked and replaced more often

Question 17

Describe nickel-cadmium batteries*

What are they commonly found in?

Answer 17

Several layers of anode and cathode material to reduce internal resistance
Cells are 1.2 V each and can be replaced individually
Near-constant voltage (CCV) makes it difficult to detect when the battery charge is low

Transport and commercial aircraft

Question 18

List advantages and disadvantages of nickel-cadmium batteries

Answer 18

Advantages:
Near constant voltage through discharge cycle
Greater power to weight ratio
Cells can be replaced individually

Disadvantages:
Expensive
Difficult to detect low battery

Question 19

List advantages and disadvantages of lithium-ion batteries

Answer 19

Advantages:
One of the best energy-to-weight ratios
No memory effect
Slow loss of charge when not using

Disadvantages:
Higher voltage
Thermal runaway

Question 20

Describe the discharge rate of alkaline, nickel cadmium, and rechargeable/lithium batteries*

Answer 20

Alkaline batteries discharge at a steady rate

Nickel Cadmium batteries discharge slowly until about 90% capacity is used then it drops quickly

Rechargeable/lithium batteries maintain a slow discharge rate from when the charger is unplugged until it reaches close to exhaustion and it just drops off (phone battery, battery discharges slowly but in the last 5%, it drops quickly)

Question 21

List batteries from lowest to highest energy to weight ratio

Answer 21

Lead acid
NiCd
NiMH
Li-ion