概念汽车实用英语毛矛概念汽车实用英语U6课件教学.pptVIP

PPT研究院 POWERPOINT ACADEMY * * READING MATERIAL： JUMP START A jump start or boost is a term for a method of starting an automobile which has a discharged battery. A second battery is temporarily connected to the dead (discharged) battery, to provide the initial charge required to start the engine. Once the engine is running, it will recharge the battery, so the second battery can be detached. However, if the engine stops running too soon, the battery may not have built up enough charge to restart the engine, so a further jump start may be required. * JUMP START Most passenger vehicles use a 12-volt battery which provides power to a starting motor for the engine. When the engine is running, electrical power from its alternator restores the charge to the battery in preparation for the next start. When a battery is discharged, such as by inadvertently leaving ones headlights switched on while parked, the cars engine will not turn over when the ignition key is turned. * JUMP START Many motorists carry jumper cables which consist of a pair of heavy gauge insulated wires with alligator clips at each end. Jumper cables are marked by black (-) and red (+) handles, representing the two polarities of the automobiles direct current system. Interchanging the polarities will cause a short circuit and a hazard to people, and damage to one or both automobiles. Good quality jumper cables will have large copper conductors and well-made alligator clips, and insulation that remains flexible at low temperatures. Longer cables require less maneuvering of the boosting vehicle to allow connection of the two batteries. * JUMP START 1. Procedure If the discharged battery is cracked, has a low electrolyte level, or is frozen, then a jump start should not be attempted. Proper jump start procedures are usually found in the owners manual for the vehicles. Owners manuals may show the preferred locations for connection of jumper cables; for example, some vehicles have the battery mounted under a s