概念汽车实用英语毛矛概念汽车实用英语U10章节.pptVIP

PPT研究院 POWERPOINT ACADEMY * * CAR BATTERY When the battery is discharged (or if the electrolyte level is too low), the float sinks and the window appears yellow (or black). The built-in hydrometer only checks the state of charge of one cell and will not show faults in the other cells. Batteries will last longer if not stored in a discharged state. * CAR BATTERY Sulfation occurs when a battery is not fully charged, and the longer it remains in a discharged state the harder it is to overcome the sulfation. This may be overcome with slow, low-current charging. Sulfation is due to formation of large, non-conductive lead sulfate crystals on the plates; lead sulfate formation is part of each cycle, but in the discharged condition the crystals become large and block passage of current through the electrolyte. * CAR BATTERY Batteries should be monitored and periodically charged if in storage, to retain their capacity. Batteries intended to be stored should be fully charged, cleaned of corrosion deposits, and left in a cool dry environment. * CAR BATTERY High temperatures increase the self discharge rate and plate corrosion. Lead-acid batteries must always be kept in a fully charged condition. The terminal voltage can be measured as an indication of state of charge. Batteries may be charged periodically by a constant voltage method. * CAR BATTERY In modern automobiles, the grounding is provided by connecting the body of the car to the negative electrode of the battery, a system called negative ground. In the past some cars had positive ground. Such vehicles were found to suffer worse body corrosion and, sometimes, blocked radiators due to deposition of metal sludge. * CAR BATTERY When changing a battery, battery manufacturers recommend disconnecting the ground connection first to prevent accidental short-circuits between the battery terminal and the vehicle frame. * CAR BATTERY The majority of automotive lead-acid batteries are filled with the appropriate electrolyte soluti