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Emergency Power Systems > Applications of Cells and Batteries > Flashcards

Applications of Cells and Batteries Flashcards

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1
Q

What is the difference between a cell and a battery?

A

A cell is the fundamental unit consisting of a positive electrode, a negative electrode, and an electrolyte solution. A battery is an arrangement of two or more cells (although a single dry cell is commonly called a battery)

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2
Q

What is the difference between a primary cell and a secondary cell?

A

A primary cell is chemically irreversible after the active ingredients have been consumed, whereas the secondary cell can be recharged

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3
Q

What does the term “dry cell” imply?

A

The electrolyte is combined with various ingredients to form a paste or gel, rather than a liquid form

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4
Q

What is another name for the carbon-zinc dry cell?

A

The Leclanche cell

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5
Q

Which primary cell with similar features is considered as the heavy-duty counterpart to the carbon-zinc cell?

A

zinc-cloride cell

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6
Q

In order to form a 9V transistor battery, how must the individual carbon-zinc cells be connected?

A

In series (six 1.5V cells)

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7
Q

What two advantages does the alkaline cell have over the standard carbon-zinc cell?

A

Greater energy capacity; longer life (during both discharge and storage)

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8
Q

In what type of case shape are silver-oxide and mercury cells commonly constructed?

A

Miniture “button” case styles

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9
Q

Which type of primary cell has the highest open-circuit voltage?

A

Lithium cell (3V)

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10
Q

Which type of primary cell is generally considered as the most expensive for its energy capacity?

A

Silver-oxide cell

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11
Q

What is a storage battery?

A

A large-capacity rechargeable battery

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12
Q

What is meant by the term “wet cell”?

A

A storage (secondary) battery that has a liquid electrolyte

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13
Q

What are the four main categories of secondary batteries?

A

Automotive (SLI) batteries; motive power batteries; standby batteries; portable batteries

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14
Q

The relative density of the electrolyte in a battery is measured with an instrument called a ________

A

Hydrometer

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15
Q

What is the relative density expected for a fully charged portable battery?

A

Between 1280 and 1300 relative density

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16
Q

What is the relative density expected for a fully charged stationary battery?

A

Between 1210 and 1225 relative density

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17
Q

What happens to the internal resistance of a lead-acid battery during normal discharge?

A

The internal resistance increases during discharge, resulting in a decrease of the battery’s terminal (working) voltage

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18
Q

What is the terminal voltage expected for a fully charged, six-cell, lead-acid battery?

A

13.2V (Six cells at 2.2V per cell)

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19
Q

How many cells are in a conventional 12V lead-acid battery?

A

6

20
Q

How many cells are in a conventional 12V nickel-iron battery?

A

10

21
Q

How many cells are in a conventional 12V nickel-cadmium battery?

A

10

22
Q

Compared to acid (in lead-acid batteries), what type of electrolyte is used in nickel-cadmium batteries?

A

Alkaline

23
Q

What is the relative density expected for a fully charged nickel-cadmium stationary battery?

A

Approximately 1200 relative density

24
Q

The relative density of a nickel-cadmium battery cannot be used as a reliable measurement of its state of charge. Why not?

A

The relative density does not change significantly during discharge (it remains constant), so it cannot be used to determine the state of charge for alkaline batteries

25
Q

How can the memory effect be overcome in a nickel-cadmium cell?

A

Discharge the battery completely; then recharge to full capacity at the recommended charging current (this may have to be repeated several times)

26
Q

What are three tasks involved in the monthly maintenance of lead-acid station batteries?

A
  • Measuring relative density of pilot cells
  • Recording temperature-corrected hydrometer readings
  • Checking electrolyte levels and adding water as necessary
  • Measuring and recording cell voltages
  • Cleaning accumulated dust from cell tops
27
Q

What are three items of personal protective equipment required when servicing wet-cell batteries?

A
  • Eye goggles
  • Rubber gloves
  • Rubber apron
28
Q

Why is it important that there be no smoking or open flames near stationary battery installations?

A

Because of the explosion hazard resulting from the presence of hydrogen gas

29
Q

What type of electrolyte solution is used for lead-acid cells?

A

Sulphuric acid and water

30
Q

What type of electrolyte solution is used for alkaline cells?

A

Potassium hydroxide and water

31
Q

Why is it good practice to insulate tool handles for use on battery installations?

A

To protect against electrical shock and accidental short circuiting of cells

32
Q

Would the indicator float in a hydrometer sink deeper or float higher in a fully charged lead-acid battery?

A

Float higher

33
Q

If the relative density of an electrolyte read 1280 at 30°C, would you expect the temperature-corrected relative density at 25°C to be higher or lower in value?

A

Higher

34
Q

Why should metal containers not be used to store distilled water for batteries?

A

Metal containers may contaminate the water (by leaching)

35
Q

Why should a non-metallic bristle brush be used to clean the tops of battery cells?

A

Metal bristles are conductive and may cause a short circuit

36
Q

Voltmeter readings of cell voltages should normally be recorded to how many decimal places?

A

Two at least two decimal places (one-hundredth)

37
Q

What is the usual charging time required to fully restore a stationary battery from its discharged condition?

A

Approximately 8 hours

38
Q

What is the name given to the charging system in which the battery and its load are connected in parallel with the rectified power source?

A

Float charge

39
Q

What type of charge is given to a standby battery in order to maintain it in a fully charged condition?

A

Trickle charge

40
Q

What are the two fundamental methods used for charging batteries?

A
  • Constant-voltage charging

- Constant-current charging

41
Q

In accordance with the CEC, what is the minimum spacing between battery cells?

A

10mm. See Rule 26-550(2)

42
Q

The mounting surface of a battery rack is usually required to have a covering of insulating material with a dielectric strength of at least ___V

A

1500V. See Rule 26-550(1)(c)

43
Q

Sufficient ventilation should be provided in battery rooms to prevent the hydrogen gas from building up to a level of ___% by volume in the room air at any time

A

2%. See Rule 26-546-Appendex B

44
Q

Lead-acid batteries should not be located in areas where the temperature is likely to fall below ___°C or rise above ____°C

A

-7°C, 45°C. See Rule 26-546-Appendex B

45
Q

Is it permitted to use MI cable for wiring between batteries?

A

Yes, if adequately protected against corrosion (where it may be in direct contact with acid or acid spray). See Rule 26-552(1)(d)

Emergency Power Systems (4 decks)

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