Automotive Electricity And Electronics

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Automotive Electricity and Electronics
Chapter 5
Automotive Batteries
* Identify the hazards associated with battery service * Explain the purposes of the battery * Describe the construction of conventional, maintenance-free, hybrid, and recombination batteries * Define the main elements of the battery * Explain the chemical action that occurs to produce current in a battery * Describe the differences, advantages, and disadvantages between different types of batteries * Describe the different types of battery terminals used * Describe the methods used to rate batteries * Determine the correct battery to be installed into a vehicle * Explain the effects of temperature on battery performance * Describe the different loads or demands placed upon a battery during different operating conditions * Explain the major reasons for battery failure * Define battery-related terms such as deep cycle, electrolyte solution, and gassing
Battery Functions: -The battery is the main source of electrical energy in the vehicle. It provides energy to operate lights and accessories and to start eh engine. -It also serves as a voltage stabilizer
Lead-Acid Battery: -Lead-acid batteries can be called by different names: * Vented * Sealed * Low maintenance * No maintenance
Battery Construction: -The battery case holds and protects all of the internal components and contains the electrolyte
Positive and Negative Plates: -Positive plates are covered with lead dioxide (PbO2) -Negative plates are made of lead (Pb)
-Insulator plates keep positive and negative plates from touching each other and shorting out

Battery Cells: -A typical automotive battery contains 6 cells connected in series. -Each cell produces 2.1 volts -12.6v = 100% -12.4v = 75%
Battery Vent Caps: -Vent caps allow the controlled release of hydrogen as the battery charges
Battery Electrolyte: -Acid in the electrolyte reacts chemically with the positive plates’ lead dioxide (PbO2) and the negative plates’ sponge lead (Pb) to produce a voltage
Lead-Acid Chemical Reaction: -The charging current causes water and lead sulfate (PbSO4) to break down and restore the electrolyte and the plates -When plates are connected, current flow breaks down electrolyte into water and lead sulfate -Eventually only water and lead sulfate remain and there is no longer any voltage -Applying a current to the battery reverses the discharge process
Conventional Battery: -Plates made of lead and 5% antimony -Need to add water because of gassing -Charges easily -Good reserve
Low Maintenance Battery: -Plates made of lead and 3.4% antimony -Less gassing -Can add water -Baffled vents
Maintenance-Free Battery: -Plates made of lead and calcium -Do not need to add water -Top of battery is sealed -Does not accept charging well -Takes longer to charge -Less reserve capacity
Hybrid Battery: -Positive plate – Lead and 2.75% antimony -Negative plate – Lead and calcium -Combines advantages of conventional and maintenance-free batteries

Recombination Battery: -Newest on the market – Optima batteries -Expensive -No liquid electrolyte -Separators hold gel -Can be installed in any position -Is corrosion free and has very low maintenance -Can last up to 4 times longer than conventional batteries -Can withstand deep cycling without damage -Can be rated over 800 cold cranking amperes (CCA) -Easily over charged
Battery Capacity Ratings: -Dependent on: -Size and number of plates -Volume and strength of electrolyte -Capacity Ratings: -Cold Cranking Amps (CCA) -Reserve Capacity (RC) -Ampere Hours (AH) -Cranking Amps (CA)
Battery Ratings: -Ampere Hour -? Amps•(20 Hours) @ 80OF = 10.5 Volts -4 Amps•(20 hours) = 80 Amp Hour -Cold Cranking Amps -? Amps for 30 sec. @ 0OF = 7.2 Volts -Cranking Amps