Batteries and Fuses Topics covered in this presentation: Battery Operating Principles Battery Construction

Objectives: By the end of this lesson you should be able to: Identify why we need a battery in a car Describe the basic construction of a battery Identify Energy Convertions State the nominal value of a cell Work out the nominal value of a battery

The Battery Electrical systems require electrical power to function. Alternator provides electrical power when engine is running. Battery provides electrical power when engine is stationary. A large amount of battery power is required to start an engine. Next >

Question 1 When is the most electrical power required from an automobile battery? A) When the headlights are turned on B) When the engine is started Correct Answer = B C) When the horn is used D) When the automobile is stationary

Fundamental battery cell Batteries - Active Materials Positive plate Negative plate Electrolyte Separator Load Fundamental battery cell Container Battery plates contain active materials that react with the electrolyte. Positive plate active material is lead peroxide, negative plate active material is porous lead. Electrolyte is made from sulphuric acid and distilled water. Next >

Question 2 What does the positive plate of a car battery contain? A) Lead B) Lead sulphate Correct Answer = C C) Lead peroxide D) Lead nitrate

Batteries - Cell Construction Positive plates Negative plates Grid Lead straps / connectors Plates Plates contain grids that hold the active material and provide an electrical path. Plate Groups Alternate positive and negative plates are grouped together, and connected by straps. Separators Separators Insulate the plates from each other, but allow electrolyte to flow freely. Next >

Batteries - Cells An element contains plate groups and separators, and is commonly known as a cell. Each cell produces about 2V, so 6 cells are required for a 12V battery. Cells are connected in series by lead straps. Straps across end cells are part of the terminals. Battery terminals Lead straps Cell (x6) Next >

Question 3 What voltage, in V, approximately, does each cell of a battery produce? Enter your answer and press SEND. Correct Answer = 1.9 - 2.1

Batteries - Discharging and Charging (described using conventional current flow techniques) Discharging Discharging occurs when current flows out of a battery. Current is produced when a load is placed across battery terminals. Battery converts stored chemical energy into electrical energy. Charging Charging occurs when current flows into battery. Requires an external voltage that is higher than the battery voltage. On a vehicle, the charging voltage is provided by an alternator. Next >

Question 4 Which of the following correctly describes the main energy change occurring when a battery is discharging? A) electrical to chemical B) potential to kinetic Correct Answer = C C) chemical to electrical D) chemical to heat and light

Batteries - Chemical Action Electrolyte chemically reacts with lead plates. Discharging Electrolyte hydrogen combines with positive plate oxygen to form water. Electrolyte sulphate combines with lead on plates to form lead sulphate. Charging Current flow reverses chemical action. Sulphate is forced back into electrolyte and combines with hydrogen, while oxygen returns to the positive plate to form lead peroxide. Process continues while voltage is applied, until all lead sulphate is converted. Next >

Question 5 As an automobile battery discharges the electrolyte becomes more dilute. Is this true or false? Answer True or False. Correct Answer = T

Batteries - Ratings Labels on battery case indicate battery ‘rating’. Capacity - Ampere-Hour Rating Amount of current a battery can supply over a given period of time (20 hours) @ 27°C (80°F). Capacity - Cold Start Rating Current battery can provide over a set period of time (30s) @ -18°C (0°F). Capacity - Reserve Capacity Rating Time battery can supply 25A @ 27°C (80°F) before the individual cell voltages drop below 1.7V. Next >

Question 6 Which of the following units measures the capacity of a battery? A) Ampere B) Volt Correct Answer = D C) Watt D) Ampere-hour

Batteries - Case Case is made of polypropylene (plastic) or a hard rubber compound. Dividers help separate cells. Ribs at bottom of each cell collect excess material from plates. Next >

Batteries - Case Cover is sealed to the top of the case. Openings above each cell for screw-in plugs or snap-in caps, in low-maintenance batteries. Next >

Batteries - Terminals and Cables Battery Terminals Battery has terminals for cable connections. Positive terminal is usually bigger. Common types are: Battery Cables Cables connect to battery using cable ends. Battery cables carry large currents and are very thick. Cables should be kept short for ease of routing. Lug or L terminal Side terminal Post terminal Next >

Question 7 Why are battery cables very thick? A) Because they carry large currents B) Because vibration causes thin cables to fracture Correct Answer = A C) Because they must not bend easily D) Because they have to be attached to large connectors

Batteries - Maintenance Free Batteries Sealed for life, no need to top-up with electrolyte. Built-in relative density indicator. Green = fully charged. Black = requires charging. Yellow = electrolyte low. Reservoir to collect evaporated water. Next >

Objectives: By the end of this lesson you should be able to: Identify why we need a battery in a car Describe the basic construction of a battery Identify the 3 main chemical parts State the nominal value of a cell Work out the nominal value of a battery

LJ 34:91 Batteries First 4 chapters