Tài liệu học tập cơ bản khái quát về động cơ và các bộ phận trên ô tô phiên bản tiếng anh. Tài liệu này nhằm giúp chúng ta tiếp cận được cấu tạo chức năng của các bộ phận của xe. Với tài liệu này giúp các bạn sinh viên ngành cơ khí ô tô tiếp cận được những kiến thức cơ bản về ô tô và đồng thời nâng cao kiến thức tiếng anh. Bộ tài liệu này được soạn thảo bởi trường đào tạo và huấn luyện nghề ở Canada.
Chapter 17 Batteries: Theory, Diagnosis, and Service Basic Battery Theory Charging • Restores chemical nature of cells • A chemical reaction causes current flow within the cells • Each battery has own charging requirement • Follow charging procedures to prevent battery damage Cell Arrangements • Voltage depends on cell materials and chemicals used • Most produce between 1.2 – 4.0 volts • To produce higher voltage, cells are connected together Series Connections Battery Hardware • Battery Cables – – – – – Must be able to carry current to meet demands 12-volt cables or gauge Connections can be top or side post Must be clean and tight HV cables on hybrid vehicles are orange Battery Hardware (cont’d) • Battery Hold-Downs – Batteries must be securely held to prevent damage – A loose battery can short against vehicle – Excessive vibration destroys plates – Can be either metal or plastic Recycling Batteries • Do not discard batteries with trash • 98% of lead-acid batteries are recycled • Additional information: – Interstate Batteries – BCI – EPA Battery Ratings • Voltage rating may be expressed as open circuit voltage – the voltage measured when there is no load on the battery • Operating voltage is measured with the battery under a load Battery Ratings (cont’d) • Cold Cranking Amps (CCA) Rating – The load in amperes that a battery can deliver for 30 seconds at 0°F (-17.7°C) without the voltage dropping below 7.2 volts • Cranking Amps (CA) Rating – Current a battery can deliver for 30 seconds at 32°F (0°C) without the voltage dropping below 7.2 volts Battery Cables • Poor connections cause voltage drops • Voltage drop across connections • Heavy corrosion is obvious but can also form a nearly invisible barrier • Damaged, bent or out-of-shape terminals will cause excessive resistance Battery Chargers • Fast Chargers – Charge quickly but can overheat battery – Battery must be in good condition – Never fast-charge a sulfated battery • Slow Chargers – Safe way to charge sulfated batteries Battery Chargers (cont’d) • Always charge in a well ventilated area • Charger should be off when connecting and disconnecting battery leads • Never attempt to charge a frozen battery • Disconnect battery cables when charging in the vehicle Replacing a Battery • When selecting a new battery, consider: – – – – – Capacity Ratings Size Meets or exceeds power requirements Fits hold-down fixtures Isolating High-Voltage Systems • Ensure HV system is shut down and isolated before working on HV component • Use insulated tools • Never leave tools near battery pack • Do not wear anything metallic Isolating High-Voltage Systems (cont)’d • Do not touch HV cables or parts without the correct protective gear • Wear HV gloves when de-powering and powering the HV system • Follow each manufacturer’s procedures for de-powering HV systems ... group of positive and negative plates formed into a group Basic Construction (cont’d) • Electrolyte is a solution of sulfuric acid and water • The sulfate reacts with the lead and lead peroxide... solution is 65% water and 35% acid Casing Design Terminals • Two terminals • Specified by the Battery Council International (BCI) Discharging and Charging Charging Maintenance-Free and Low-Maintenance... Inspection Tips • Check the case for damage, dirt, and corrosion • Check the electrolyte level, color, and odor • Check the case for cracks and loose terminal posts • Check the condition of the