AUTOMOTIVE battery , LE THANH PHUC

University of Technical Education Ho Chi Minh City AUTOMOTIVE BATTERIES Le Thanh Phuc Faculty of Automotive Engineering Email: thanhphucckd@gmail.com Introduction A lead-acid storage battery is an electrochemical device that produces voltage and delivers electrical current It's important to remember that a battery does not store electricity, but rather it stores a series of chemicals, and through a chemical process electricity is produced The purpose of the battery ENGINE IS OFF: Electricity from the battery is used to operate lighting accessories, or other electrical systems ENGINE IS STARTING: Electricity from the battery is used to operate the starter motor ENGINE IS RUNNING: Electricity from the battery may be needed to supplement the charging system Battery construction An automobile battery contains a diluted sulfuric acid electrolyte and positive and negative electrodes, in the form of several plates Cell element Positive plates and negative plates are each connected together by separate plate straps Grouping the plates in this way serves to enlarge the surface area between the active materials and the electrolyte Plates Battery plates are constructed of a lead alloy containing a percentage of either Antimony or Calcium The grid provides the necessary framework for active material to be pasted onto the plate The active material on a charged positive plate is Lead Dioxide (PbO2), the active material on a charged negative plate is a Sponge Lead (Pb) Electrolyte Battery electrolyte is a mixture of 36% sulfuric acid (H2SO4) and 64% distilled water (H20) Batteries today have an electrolyte with a specific gravity of 1.270 (at 200C) when fully charged Specific gravity of electrolyte Electrolyte in a charged battery is stronger and heavier than electrolyte in a discharged battery The specific gravity of water is 1.000, and the specific gravity of sulfuric acid is 1.835, which means the acid is 1.835 times heavier than the water Cell operation Two dissimilar metals placed in an acid bath produce electrical potential across the poles The cell produces voltage by a chemical reaction between the plates and the electrolyte Cycling The battery stores electricity in the form of chemical energy The cycle of discharging and charging is repeated continuously and is called “battery Cycling” 10 Cell voltage Each cell element of the battery produces approximately 2.1 volts, regardless of the quantity or size of the plates Automobile batteries have six cells that are connected in series, which produces a total voltage of 12.6 volts 11 Battery rating Ampere hour capacity: A battery quoted as being 44Ah (ampere-hour) will be able, if fully charged, to supply 2.2 A for 20 hours before being completely discharged (cell voltage above 1.75 V) Reserve capacity: This is quoted as a time in minutes for which the battery will supply 25 A at 25°C to a final voltage of 1.75V per cell Typically, a 44 Ah battery will have a reserve capacity of about 60 minutes Cold cranking amps: A typical value of 170A means that the battery will supply this current for one minute at a temperature of 18°C, at 12 which point the cell voltage will fall to 1.4 V Battery charging 13 14 [...]... Each cell element of the battery produces approximately 2.1 volts, regardless of the quantity or size of the plates Automobile batteries have six cells that are connected in series, which produces a total voltage of 12.6 volts 11 Battery rating Ampere hour capacity: A battery quoted as being 44Ah (ampere-hour) will be able, if fully charged, to supply 2.2 A for 20 hours before being completely discharged... as a time in minutes for which the battery will supply 25 A at 25°C to a final voltage of 1.75V per cell Typically, a 44 Ah battery will have a reserve capacity of about 60 minutes Cold cranking amps: A typical value of 170A means that the battery will supply this current for one minute at a temperature of 18°C, at 12 which point the cell voltage will fall to 1.4 V Battery charging 13 14 ... produces a total voltage of 12. 6 volts 11 Battery rating Ampere hour capacity: A battery quoted as being 44Ah (ampere-hour) will be able, if fully charged, to supply 2. 2 A for 20 hours before being... specific gravity of 1 .27 0 (at 20 0C) when fully charged Specific gravity of electrolyte Electrolyte in a charged battery is stronger and heavier than electrolyte in a discharged battery The specific... Dioxide (PbO2), the active material on a charged negative plate is a Sponge Lead (Pb) Electrolyte Battery electrolyte is a mixture of 36% sulfuric acid (H2SO4) and 64% distilled water (H20) Batteries