BATTERIES

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BATTERIES

• Heart of the electrical system

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Functions

• Supply energy to electrical systems when the
  vehicle is not running
• Operating cranking system
• Store energy
• Supply extra power when demand exceeds supply

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THE GALVANIC REACTION

• Creates a charge differential by chemical
  reaction
• Production of current when two dissimilar metals
  are placed in electrolyte
• Creates corrosion between dissimilar metals
  steel aluminum

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TYPES OF BATTERIES

• The term battery means a collection of galvanic
  cells connected
• Current 12 volt batteries have 6 series-connected
  cells housed in a polypropylene case
• Each cell has positive and negative plates anode
  cathode

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• The negative plates are connected to each other
  and so are the positive plates
• Negative and positive plates are arranged
  alternately in each cell
• Positive and negative plates are insulated from
  each other by electrically insulating separator
  plates
• This assembly is submerged in cell case full of
  electrolyte, 64 water 36 sulfuric acid

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CELL CONNECTORS

• Cell elements are connected in series
• Positive strap of one cell is connected to
  negative strap of the adjacent cell
• Connections are made through the cell partitions
  in the case or over the top of the partitions

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PLATES

• Plates are cast from lead
• Then are covered in a paste unique to the
  polarity of each plate
• Positive plate paste is made from lead oxide
• Negative plate paste is sponge lead
• Antimony is added to plate material to minimize
  corrosion

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SEPERARTOR PLATES

• Prevent the battery grid plates from shorting out
• Thin glass fiber plates
• Allows electrolyte to flow easily through out
  cell while insulating the plates from each other
• Plates sometimes shed the paste that was bonded
  to them at manufacturing commonly caused by
  vibration or deep cycling
• To prevent this from shorting out sediment
  chambers are used to collect this material

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ELECTROLYTE

• Battery acid electrolyte is typically 36
  sulphuric acid and 64 water
• Electrolyte is measured by specific gravity
• Specific gravity is the weight of a liquid or
  solid versus that of the same volume of water
• Specific gravity of water is 1.000
• Specific gravity of electrolyte is 1.265 at 80
  degrees F

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• When specific gravity is low the battery is said
  to be what??
• In a state of discharge
• Battery could freeze in colder climates
• If specific gravity is too high the plate grids
  in the battery could be damaged
• Battery acid is very corrosive and will cause
  skin and eye damage, clothing, metal and painted
  surfaces damage

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84 FACTOR

• Actual specific gravity of electrolyte in any
  cell in a battery relates directly to its voltage
• Voltage can be calculated by adding .840 to the
  specific gravity reading
• 1.265 0.840 2.100 volts

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DISCHARGE CYCLE

• The positive plate reacts with the sulfuric acid,
  which results in an oxygen molecule being
  released into the electrolyte
• The negative plate reacts with the electrolyte to
  form lead sulfate
• The action will occur until both the positive and
  negative plates are coated with lead sulfate

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CHARGE CYCLE

• The sulfate coatings on the plates are returned
  to reform electrolyte
• Water molecules are reduced to hydrogen and
  oxygen
• The hydrogen combines the electrolyte to form
  sulfuric acid
• The oxygen is drawn to the positive plates to
  reconstruct the lead peroxide coating

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• When a battery is in the charge cycle, gassing is
  caused by electrolysis.
• Gassing is the conversion of water in the
  electrolyte to hydrogen and oxygen gas
• Forming an explosive combination!!!

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DEEP CYCLE BATTERIES

• Similar in many respects to the standard battery
• However plates are made much thicker to avoid?
• Buckling caused by the heat created internal
  resistance

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SULFATION

• Condition occurs when battery becomes discharged
  to the point that the sulfate coating hardens on
  the plates and can no longer be converted

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MAINTENANCE-FREE BATTERIES

• Essentially the same construction as lead
  batteries
• Uses substances such as calcium, cadmium, and
  strontium instead of antimony on the plates
• These substances reduce gassing during the
  charging cycle
• Additionally an expansion or condensing chamber
  is used to contain the gassing

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GELLED ELECTROLYTE BATTERIES

• Gel cell
• Similar to standard electrolyte batteries
• Main difference of the gel cell is the
  electrolyte
• The gel battery uses a special thixotropic
  electrolyte that when stirred or shaken liquefies
  but returns to the gelled state when left at rest

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ADVANTAGES

• For this reason it never requires refilling
• Spill-proof and leak-proof
• Vent no oxygen or hydrogen during charging
• Vibration resistant
• Double the service life of maintenance free
  battery
• Can sustain deep cycling

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DISADVANTAGES

• Weigh more
• Will fail if overcharged
• Requires special chargers automatic,
  temperature-sensing, voltage-regulated
• Vulnerable to abuse