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  • Figure 50-1 Batteries are constructed of plates grouped into cells and installed in a plastic case
  • Figure 50-2 A grid from a battery used in both positive and negative plates.
  • Figure 50-3 Two groups of plates are combined to form a battery element.
  • Figure 50-4 A cutaway battery showing the connection of the cells to each other through the partition.
  • Figure 50-5 Chemical reaction for a lead-acid battery that is fully charged being discharged by the attached electrical load.
  • Figure 50-6 Chemical reaction for a lead-acid battery that is fully discharged being charged by the attached generator.
  • Figure 50-7 As the battery becomes discharged, the specific gravity of the battery acid decreases.
  • Figure 50-8 Typical battery charge indicator. If the specific gravity is low (battery discharged), the ball drops away from the reflective prism. When the battery is charged enough, the ball floats and reflects the color of the ball (usually green) back up through the sight glass and the sight glass is dark.
  • Chart 50-1 A comparison showing the relationship among specific gravity, battery voltage, and state of charge.
  • Figure 50-9 An absorbed glass mat battery is totally sealed and is more vibration resistant than conventional lead-acid batteries.
  • Figure 50-10 A typical battery hold-down bracket. All batteries should use a bracket to prevent battery damage due to vibration and shock.
  • Figure 50-11 This battery has a cranking amperes (CA) rating of 1,000. This means that this battery is capable of cranking an engine for 30 seconds at a temperature of 32°F (0°C) at a minimum of 1.2 volts per cell (7.2 volts for a 12 volt battery).

Halderman ch050 lecture Halderman ch050 lecture Presentation Transcript

  • BATTERIES 50
  • Objectives
    • The student should be able to:
      • Prepare for ASE Electrical/Electronic Systems (A6) certification test content area “B” (Battery Diagnosis and Service).
      • Describe how a battery works.
      • List battery ratings.
      • Describe deep cycling.
      • Discuss how charge indicators work.
  • INTRODUCTION
  • Introduction
    • Purpose and Function
      • Everything electric in a vehicle gets current from the battery
      • Primary purpose of battery is to provide electrical power for starting and demands that exceed alternator output
  • Introduction
    • Why Batteries Are Important
      • Battery acts as stabilizer to voltage in entire electrical system
      • Serves as reservoir where large amounts of current can be removed quickly
  • Introduction
    • Why Batteries Are Important
      • Battery must be in serviceable condition before charging and cranking systems can be tested
      • Charging system could test as defective because of weak or discharged battery
  • Introduction
    • Why Batteries Are Important
      • Test battery before further testing of cranking or charging system
  • BATTERY CONSTRUCTION
  • Battery Construction
    • Case
      • Most automotive battery cases are constructed of polypropylene
      • Inside case are six cells (for 12 volt battery)
  • Figure 50-1 Batteries are constructed of plates grouped into cells and installed in a plastic case
  • Battery Construction
    • Case
      • Each cell has positive and negative plates
      • Built into bottom of many batteries are ribs to support lead-alloy plates and provide sediment chamber
  • Battery Construction
    • Case
      • Maintenance-free battery uses little water during normal service
      • Maintenance-free batteries are also called low-water-loss batteries
  • Battery Construction
    • Grids
      • Each positive and negative plate is constructed on framework, or grid
      • Grid made primarily of lead
  • Battery Construction
    • Grids
      • Lead must be strengthened for use in automotive battery grid
      • Antimony or calcium added to lead for strength
    ?
  • Figure 50-2 A grid from a battery used in both positive and negative plates.
  • Battery Construction
    • Grids
      • Battery grids hold active material and provide electrical pathways for current created in plate
  • Battery Construction
    • Grids
      • Maintenance-free batteries use calcium instead of antimony
      • 0.2% calcium has same strength as 6% antimony
  • Battery Construction
    • Grids
      • Typical lead-calcium grid uses only 0.09% to 0.12% calcium
      • Using lower amounts of calcium instead of higher amounts of antimony reduces gassing
  • Battery Construction
    • Grids
      • Gassing results in water usage
      • Low-maintenance batteries use low percentage of antimony or use antinomy only in positive grids and calcium in negative grids
  • Battery Construction
    • Grids
      • Percentages that make up the alloy of plate grids make the major difference between standard and maintenance-free batteries
  • Battery Construction
    • Positive Plates
      • Positive plates have lead dioxide (peroxide) in paste form placed onto grid framework
  • Battery Construction
    • Positive Plates
      • The process is called pasting
      • Lead dioxide reacts with sulfuric acid of battery
  • Battery Construction
    • Negative Plates
      • Pasted to the grid with a pure porous lead called sponge lead
  • Battery Construction
    • Separators
      • Positive and negative plates installed alternately next to each other without touching
  • Battery Construction
    • Separators
      • Nonconducting separators are used
      • Separators allow room for reaction of acid with both plate materials
  • Battery Construction
    • Separators
      • Separators insulate plates to prevent shorts
      • Separators are porous and have ribs facing positive plate
  • Battery Construction
    • Separators
      • Separators are made from resin-coated paper, porous rubber, fiberglass, or plastic
      • Many batteries use envelope-type separators to encase entire plate
  • Battery Construction
    • Cells
      • Cells constructed of positive and negative plates
      • Insulating separators between each plate
  • Battery Construction
    • Cells
      • Most batteries use one more negative plate than positive plate in each cell
      • Many newer batteries use equal number of positive and negative plates
  • Battery Construction
    • Cells
      • Cell is also called element
      • Each cell is actually a 2.1 volt battery
  • Battery Construction
    • Cells
      • Greater the number of plates in each cell, the greater the amount of current produced
      • Typical batteries contain four positive and five negative plates per cell
  • Figure 50-3 Two groups of plates are combined to form a battery element.
  • Battery Construction
    • Cells
      • 12-volt battery has six cells connected in a series and producing 12.6 volts
      • Amperage capacity of battery is determined by amount of active plate material and area of plate material exposed to the electrolyte
  • Battery Construction
    • Partitions
      • Each cell is separated from other cells by partitions
      • Partitions made of same material as outside case
  • Battery Construction
    • Partitions
      • Electrical connections between cells made by lead connectors looped over top of partition
      • Many batteries connect cells through partition connectors
  • Figure 50-4 A cutaway battery showing the connection of the cells to each other through the partition.
  • Battery Construction
    • Electrolyte
      • Electrolyte is the acid solution in a battery
      • Electrolyte in automotive batteries is a solution of 36% sulfuric acid and 64% water (H 2 SO 4 )
  • Battery Construction
    • Electrolyte
      • H 2 = symbol for hydrogen (subscript 2 indicates two atoms of hydrogen)
      • S = symbol for sulfur
  • Battery Construction
    • Electrolyte
      • O 4 = symbol for oxygen (subscript 4 indicates 4 atoms of oxygen)
      • Electrolyte is factory installed or added when battery is sold
  • Battery Construction
    • Electrolyte
      • Additional electrolyte should never be added after original fill
      • Only pure distilled water should be added to battery
  • HOW A BATTERY WORKS
  • How a Battery Works
    • Principle Involved
      • When two dissimilar metals are placed in acid, electrons flow between the metals if a circuit connects them
  • How a Battery Works
    • Principle Involved
      • Demonstration: push a steel nail and piece of solid copper in a lemon
      • Connect voltmeter to ends of copper wire and nail
  • How a Battery Works
    • Principle Involved
      • Voltage will be displayed
      • Fully-charged lead-acid battery has positive plate of lead dioxide and negative plate of lead surrounded by sulfuric acid solution
      • Difference in potential voltage is 2.1 volts
  • How a Battery Works
    • During Discharging
      • Positive plate lead dioxide combines with SO 4 forming PbSO 4
      • O 2 is released into electrolyte and forms H 2 O
      • Negative plate combines with the SO 4 and becomes lead sulfate (PbSO 4 )
  • Figure 50-5 Chemical reaction for a lead-acid battery that is fully charged being discharged by the attached electrical load.
  • How a Battery Works
    • Fully Discharged State
      • When battery is fully discharged, both positive and negative plates are PbSO 4 and electrolyte has become water
  • How a Battery Works
    • Fully Discharged State
      • There is a danger of freezing when battery is discharged
      • CAUTION: Never charge or jump start a frozen battery because the hydrogen gas can get trapped in the ice and ignite if a spark is caused during the charging process. The result can be an explosion.
  • How a Battery Works
    • During Charging
      • During charging, sulfate from acid leaves both positive and negative plates and returns to the electrolyte
      • Positive plate returns to lead dioxide (PbO 2 )
  • How a Battery Works
    • During Charging
      • Negative plate returns to pure lead (Pb)
      • Electrolyte becomes H 2 SO 4
    ?
  • Figure 50-6 Chemical reaction for a lead-acid battery that is fully discharged being charged by the attached generator.
  • SPECIFIC GRAVITY
  • Specific Gravity
    • Definition
      • Amount of sulfate in electrolyte is determined by electrolyte’s specific gravity
      • Specific gravity is ratio of weight of a given volume of a liquid to the weight of an equal volume of water
  • Specific Gravity
    • Definition
      • Pure water is the basis for this measurement
      • The higher the battery’s specific gravity, the more fully charged it is
  • Figure 50-7 As the battery becomes discharged, the specific gravity of the battery acid decreases.
  • Specific Gravity
    • Charge Indicators
      • Some batteries have state-of-charge indicator, called green eyes
      • Indicator is a small, ball-type hydrometer installed in one cell
      • Plastic ball floats if electrolyte density is sufficient
  • Figure 50-8 Typical battery charge indicator. If the specific gravity is low (battery discharged), the ball drops away from the reflective prism. When the battery is charged enough, the ball floats and reflects the color of the ball (usually green) back up through the sight glass and the sight glass is dark.
  • Specific Gravity
    • Charge Indicators
      • The hydrometer only tests one cell out of six and ball can easily stick
      • Do not trust the indicator to be accurate
  • Chart 50-1 A comparison showing the relationship among specific gravity, battery voltage, and state of charge.
  • VALVE REGULATED LEAD-ACID BATTERIES
  • Valve Regulated Lead-Acid Batteries
    • Terminology
      • Two basic types of valve regulated lead-acid (VRLA) batteries
      • Absorbed glass mat (AGM) battery
        • Acid is totally absorbed into the separator
        • Battery is leakproof and spillproof
  • Valve Regulated Lead-Acid Batteries
    • Terminology
      • Absorbed glass mat (AGM) battery
        • Battery is assembled by compressing the cell about 20%
  • Valve Regulated Lead-Acid Batteries
    • Terminology
      • Absorbed glass mat (AGM) battery
        • Compressed cell helps reduce damage by vibration
  • Valve Regulated Lead-Acid Batteries
    • Terminology
      • Absorbed glass mat (AGM) battery
        • Compressed cell keeps acid tight against plates
  • Valve Regulated Lead-Acid Batteries
    • Terminology
      • Absorbed glass mat (AGM) battery
        • Sealed maintenance-free design uses pressure release valve in each cell
  • Valve Regulated Lead-Acid Batteries
    • Terminology
      • Absorbed glass mat (AGM) battery
        • Most hydrogen and oxygen given off during charging remain in battery
  • Valve Regulated Lead-Acid Batteries
    • Terminology
      • Absorbed glass mat (AGM) battery
        • Separator is only 90% to 95% saturated with electrolyte; portion of mat can absorb gas
  • Valve Regulated Lead-Acid Batteries
    • Terminology
      • Absorbed glass mat (AGM) battery
        • Gas spaces provide space for hydrogen and oxygen to recombine
  • Valve Regulated Lead-Acid Batteries
    • Terminology
      • Absorbed glass mat (AGM) battery
        • AGM batteries have longer service life—7 to 10 years
  • Figure 50-9 An absorbed glass mat battery is totally sealed and is more vibration resistant than conventional lead-acid batteries.
  • Valve Regulated Lead-Acid Batteries
    • Terminology
      • Gelled electrolyte batteries
        • Silica is added to electrolyte in these batteries
  • Valve Regulated Lead-Acid Batteries
    • Terminology
      • Gelled electrolyte batteries
        • Silica turns electrolyte into substance like gelatin
        • Sometimes called gel battery
  • Valve Regulated Lead-Acid Batteries
    • Terminology
      • AGM and gel batteries called recombinant battery design
      • Oxygen generated in positive plate travels through electrolyte to negative plate
  • Valve Regulated Lead-Acid Batteries
    • Terminology
      • Oxygen reacts to lead in negative plate, which consumes the oxygen and prevents formation of hydrogen gas
      • The oxygen recombination explains why VRLA batteries do not use water
  • CAUSES AND TYPES OF BATTERY FAILURE
  • Causes and Types of Battery Failure
    • Normal Life
      • Most automotive batteries have service life of three to seven years
      • Proper care can increase battery life
      • Major cause of premature battery failure is overcharging
  • Causes and Types of Battery Failure
    • Charging Voltage
      • Automotive charging circuit consists of alternator and connecting wires
        • Charging voltages higher than 15.5 volts can damage battery
  • Causes and Types of Battery Failure
    • Charging Voltage
      • Automotive charging circuit consists of alternator and connecting wires
        • AGM batteries can be damaged if charge is higher than 14.5 volts
  • Causes and Types of Battery Failure
    • Charging Voltage
      • Overcharging causes plate material to disintegrate
      • Vibration and bumping can also cause internal damage
  • Causes and Types of Battery Failure
    • Charging Voltage
      • If one cell in 12 volt battery is shorted, battery has only 10 volts
      • Starter usually will not start engine with only 10 volts available
  • Causes and Types of Battery Failure
    • Battery Hold-Downs
      • Batteries are attached to vehicle to prevent battery damage
      • Battery hold-downs help reduce vibration
  • Figure 50-10 A typical battery hold-down bracket. All batteries should use a bracket to prevent battery damage due to vibration and shock.
  • BATTERY RATINGS
  • Battery Ratings
    • Batteries are rated by amount of current they produce under specific conditions
    • Cold-Cranking Amperes
      • Cold-cranking ampere rating is number of amperes that can be supplied by battery at 0°F (−18°C) for 30 seconds while battery maintains 1.2 volts per cell or higher
  • Battery Ratings
    • Batteries are rated by amount of current they produce under specific conditions
    • Cold-Cranking Amperes
      • Cold-cranking performance is called cold-cranking amperes (CCA)
  • Battery Ratings
    • Cranking Amperes
      • Designation CA refers to number of amperes that can be supplied by a battery at 32°F (0°C)
  • Figure 50-11 This battery has a cranking amperes (CA) rating of 1,000. This means that this battery is capable of cranking an engine for 30 seconds at a temperature of 32°F (0°C) at a minimum of 1.2 volts per cell (7.2 volts for a 12 volt battery).
  • Battery Ratings
    • Marine Cranking Amperes
      • Marine cranking amperes (MCA) is similar to cranking amperes
      • MCA is tested at 32°F (0°C)
  • Battery Ratings
    • Reserve Capacity
      • Reserve capacity rating is the number of minutes for which battery can produce 25 amperes and still have voltage of 1.75 volts per cell
  • Battery Ratings
    • Reserve Capacity
      • Rating is measurement of how long a vehicle can be driven in event of charging system failure
    ?
  • Battery Ratings
    • Ampere Hour
      • Ampere hour is an older battery rating system
      • Measures how many amperes of current a battery can produce over a period of time
  • Battery Ratings
    • Ampere Hour
      • Example: A 50 amp-hour (A-H) rating can deliver 50 amperes for one hour or 1 ampere for 50 hours
    ?
  • BATTERY SIZES
  • Battery Sizes
    • BCI Group Sizes
      • Battery sizes are standardized by Battery Council International (BCI)
      • Check the specified group number in service information, battery application charts at parts stores, or the owner’s manual
  • Battery Sizes
    • Typical Group Size Applications
      • 24/24F (top terminals): fits many Honda, Acura, Infinity, Lexus, Nissan, and Toyota vehicles
  • Battery Sizes
    • Typical Group Size Applications
      • 34/78 (dual terminals, both side and top posts): fits many General Motors pickups and SUVs, as well as midsize and larger GM sedans and large Chrysler/Dodge vehicles
  • Battery Sizes
    • Typical Group Size Applications
      • 35 (top terminals): fits many Japanese brand vehicles
  • Battery Sizes
    • Typical Group Size Applications
      • 65 (top terminals): fits most large Ford/Mercury passenger cars, trucks, and SUVs
  • Battery Sizes
    • Typical Group Size Applications
      • 75 (side terminals): fits some General Motors small and midsize cars and some Chrysler/Dodge vehicles
  • Battery Sizes
    • Typical Group Size Applications
      • 78 (side terminals): fits many General Motors pickups and SUVs, as well as midsize and larger GM sedans
      • Exact dimensions can be found on the Internet by searching for BCI battery sizes
  • FREQUENTLY ASKED QUESTION
    • What Is an SLI Battery?
      • Sometimes the term SLI is used to describe a type of battery. SLI means starting, lighting, and ignition, and describes the use of a typical automotive battery. Other types of batteries used in industry are usually batteries designed to be deep cycled and are usually not as suitable for automotive needs.
    ? BACK TO PRESENTATION
  • FREQUENTLY ASKED QUESTION
    • Is There an Easy Way to Remember How a Battery Works?
      • Yes. Think of the sulfuric acid solution in the electrolyte being deposited, then removed from the plates.
        • During discharge. The acid (SO4) is leaving the electrolyte and getting onto both plates.
    ? BACK TO PRESENTATION During charging. The acid (SO4) is being forced from both plates and enters the electrolyte.
  • FREQUENTLY ASKED QUESTION
    • What Determines Battery Capacity?
      • The capacity of any battery is determined by the amount of active plate material in the battery. A battery with a large number of thin plates can produce high current for a short period. If a few thick plates are used, the battery can produce low current for a long period.
    ? BACK TO PRESENTATION
    • A trolling motor battery used for fishing must supply a low current for a long period of time. An automotive battery is required to produce a high current for a short period for cranking. Therefore, every battery is designed for a specific application.
  • FREQUENTLY ASKED QUESTION
    • What Is Deep Cycling?
      • Deep cycling is almost fully discharging a battery and then completely recharging it. Golf cart batteries are an example of lead-acid batteries that must be designed to be deep cycled. A golf cart must be able to cover two 18-hole rounds of golf and then be fully recharged overnight.
    ? BACK TO PRESENTATION
    • Charging is hard on batteries because the internal heat generated can cause plate warpage, so these specially designed batteries use thicker plate grids that resist warpage. Normal automotive batteries are not designed for repeated deep cycling.