3.5 - DC Sources of Electricity - 4q

Question 1

Each battery consists of cells connected ….

Answer 1

in series

Question 2

What is a primary cell?

Answer 2

Electrolyte in paste form

Discharge from one plate

-electrolyte becomes weaker and eventually plate destroyed

CANNOT BE RECHARGED

Question 3

What is a Secondary Cell?

Answer 3

CAN BE RECHARGED

by passing current in opposite direction to how it was discharged

Question 4

What does the terminal voltage of a cell depend on?

Answer 4

The terminal voltage of a cell depends on the material of the plates and the electrolyte used

Question 5

What is the voltage of the following single cell:

Carbon/Zinc cell (dry cell)

Answer 5

1.5 V

Question 6

What is the voltage of the following single cell:

lead/acid

Answer 6

2 V

Question 7

What is the voltage of the following single cell:

Nickel/Cadmium

Answer 7

1.2 V

Question 8

What does cell capacity depend on?

Answer 8

The area of the plates

The larger the area of the plate, the greater the amount of active material and therefore the higher the capacity, that is the amount of current the call is capable of supplying

Question 9

When the cell is supplying current, the terminal voltage will reduce if there is :

1.

2.

Answer 9

An increase in load current

An increase in cell internal resistance

Question 10

The cell internal resistance is affected by:

1.

2.

Answer 10

Temperature

State of charge

Question 11

What is the effect of increasing temperature in a battery cell?

Answer 11

An increase of temperature will increase the resistance of the metal, but will reduce the resistance of the electrolyte. The overall effect of an increase of temperature is to reduce the internal resistance

Question 12

What is the formula associated with the internal resistance of a cell?

Answer 12

Question 13

What are thermocouples used to measure on aircraft and corresponding material?

Answer 13

Thermocouples are used on aircraft to measure:

exhaust gas temperature - Chromel and Alumel

Cylinder head temperature - Constantan and Copper

Question 14

What forms on the plates as the cell discharges>

Answer 14

Lead Sulphate forms on both plates as the cell discharges and acts as an insulator. This reduces the effective area of the plate.

Question 15

What is a Sediment well used for?

Answer 15

Plates shed when in used in the cell. These plates must be raised high enough to clear the bottom of the container or else the material may short the plates.

Question 16

Carbon/Zinc battery

Answer 16

Question 17

Lead Acid Battery:

The cell contains two ____ _____ and an _____

A cell stores _____ _____ and converts it to ____ ______

Answer 17

dissimilar elements

Electrolyte

Chemical energy

Electrical energy

Question 18

Lead Acid Battery:

A primary cell _____ be charged

A secondary cell _____ be charged

Answer 18

cannot

can

Question 19

Lead Acid Battery:

Cell voltage depends on _____ ____ and ______

____ ______ is the amount of current a cell is capable of supplying size of plates

Answer 19

electrode material

electrolyte

Cell capacity

Question 20

Lead Acid Battery:
Cells in series _____ the _____

Cells in parallel _____ the _____

Answer 20

increase

voltage

increase

capacity

Question 21

What are the three basic types of alkaline cells?

Answer 21

Nickel Cadmium (NiCad)

Nickel Iron (Ni/Fe)

Silver/Zinc (Ag/Zn)

Question 22

How many cells are required for 24V of NiCad vs Lead Acid

Answer 22

NiCad single cell 1.2 = 20 cells

Lead Acid 2V (varying) = 12 cells

Question 23

What is the electrolyte of Nickel Cadmium?

Answer 23

Electrolyte is a solution of:

Potassium Hydroxide and Distilled or De-ionised water

Question 24

What are the 3 primary functions of the cell cap or vent cap of a cell?

Answer 24

1. To prevent foreign objects entering the cell
2. To allow inspection or adjustment of the level of the electrolyte
3. To permit gassing (hydrogen and oxygen)

Question 25

What 4 things would happen if large quantities of oxygen do reach the negative plate because of a damaged gas barried?

Answer 25

1. Loose voltage
2. increase temperature
3. decrease internal resistance
4. Increase charge current (Thermal Runaway)

Question 26

When making a solution of Nickel Cadmium electrolyte, how should this be done?

Answer 26

AAA - Always Add acid or Alkali

Slowly add Potassium Hydroxide to the water

NOT VISE VERSA

Question 27

How do you determine if a Ni/Cd battery is fully charged?

Answer 27

There is only one precise method to determine if a Ni/Cd cell is fully charged and that is to fully discharge it as a measured rate against time.