ELECTRICAL I LESSON 2 BATTERY SERVICE

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ELECTRICAL ILESSON 2BATTERY SERVICE

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  this lesson.

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Battery capacity ratings

• Battery capacity ratings are set up by the
  Battery Council International (BCI) and the
  Society of Automotive Engineers (SAE). The
  ratings show the batterys ability to deliver
  current and voltage under different conditions.
  A batterys ability to deliver current depends
  on
• The surface area of the plates
• The mass of the plate material
• The mass of sulfuric acid in the electrolyte
• Internal Resistance
• Battery Temperature

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Rating Methods

• Ampere-Hour Rating
• The amount of current a battery can produce for
  20 hours at 80oF before its voltage drops below
  10.5 volts (1.75v per cell).
• 3 amps for 20 hours would be 60A-hr.

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Rating Methods

• Cold Cranking Rating
• The amount of current a battery can produce for
  30 seconds at 0oF before its voltage drops below
  7.2 volts. (1.2v per cell)

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Rating Methods

• Reserve Capacity Rating
• The number of minutes a battery can produce 25
  amps before its voltage falls below 10.5 volts
  (1.75v per cell)

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Battery Size

• A BCI group number identifies a battery by size
  dimensions, post arrangement, voltage, and hold
  down location. A battery manufacturer may make a
  variety of current capacity batteries in the same
  group. (see chart in AE1 Manual)

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Battery Installation Requirements

• Close to starter and alternator or generator
• Away from exhaust components
• Held down securely to reduce vibration
• Accessible for service

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Battery Output Requirements
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Multiple Battery Connections

• Series
• Batteries connected in series will increase the
  overall voltage. The current capacity will be
  limited to the lowest rated battery.

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Multiple Battery Connections

• Parallel
• Batteries connected in parallel will increase the
  overall current if the voltages are the same.

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Multiple Battery Connections

• Series - Parallel
• Batteries connected in series-parallel increases
  both voltage and current.

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Causes for Battery Failure

• Overcharging
• Excessive current through the battery caused by
  extra high charging voltage generates excess
  heat. The heat can cause plate warpage and
  shedding. Heat also creates evaporative
  electrolyte loss. Internal battery temperature
  should be kept below 120oF.
• Undercharging
• A battery that is partially discharged has lead
  sulfate (PbSO4) in the plate material. If the
  battery is not recharged completely, the lead
  sulfate crystallizes and then the battery plate
  material can not be restored by recharging. This
  condition is called a sulfated battery.
• A battery that is stored for a period of months
  will discharge internally and a sulfated
  condition will result.
• Concrete floor myth!!!

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Causes for Battery Failure

• Excessive Deep Cycling
• When a starting battery is completely discharged
  and recharged repeatedly the plate material will
  shed from the grid and reduce the current
  capacity.
• Vibration
• Vibration causes the plate material to fall off
  the grid. The plate material may collect in the
  bottom of the cell and short the positive and
  negative plates together. Vibration can also
  cause open internal connections between cells.

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Battery Service and Testing
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Battery Service

• Safety Precautions
• keep sparks and flames away
• charge in a well-ventilated area
• charger should be UNPLUGGED and TURNED OFF before
  connecting to a battery, in a well-ventilated
  area
• remove jewelry
• add only distilled water to a battery
• never attempt to charge or boost a frozen battery
• always disconnect the negative (ground) cable
  first and reconnect it last
• do not pound on cable clamps

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Battery Service

• Battery Inspection
• check case for physical damage or missing caps
• check case for dirt and moisture which could
  cause current flow across the case. Clean with
  baking soda water.
• check for electrolyte leakage around battery
  posts
• check for post and cable corrosion or damage
• check condition of hold down
• check heat shield condition
• check electrolyte level if possible, it should
  cover the top of the cell plates

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Battery Testing

• State-of-Charge
• Load or Capacity Test
• 3 - minute charge test

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State-of-Charge

• Two Methods Open Circuit Voltage Specific
  Gravity
• Open circuit voltage - OCV
• Using a digital voltmeter of 0.5 or better
  accuracy, measure the battery voltage when it is
  not loaded at 80oF. Check electrolyte level
  before measuring voltage.
• 12.6v gt fully charged
• 12.4v gt 75 charged
• 12.2v gt 50 charged
• If the batterys voltage is above 12.6v, it has a
  surface charge that must be removed. Load the
  battery for 15 to 30 seconds (100A) with a carbon
  pile or the starter. Allow voltage to stabilize
  for 2 minutes before re-measuring OCV.

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State-of-Charge cont

• Specific Gravity
• Compares the density of the electrolyte to that
  of water to determine state of charge. An
  hydrometer is used to measure the specific
  gravity of the electrolyte at 80oF. The reading
  must be adjusted if the electrolyte temperature
  is above or below 80oF.
• Add 0.004 for every 10o above 80o.
  
  Subtract 0.004 for every 10o below 80o.
• 1.260 - 1.280 gt fully charged
• 1.230 - 1.250 gt 75 charged
• 1.200 - 1.220 gt 50 charged.
• If the difference between cells is 0.050, replace
  the battery.
• see pg.181, vol. II

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Load or Capacity Test

• This test determines the batterys ability to
  deliver a large amount of current while
  maintaining its voltage at a usable level. The
  battery must be at least 75 charged when
  performing this test.
• Using a carbon pile load the battery, for 15
  seconds, to ½ the CCA or 3 times the ampere-hour
  rating. The voltage should remain at least 9.6v
• If the battery is not marked for its rated
  capacity use the following guide lines for load
  Engine Displacement Load Current
  Less than
  3.0L 170A 3.0L to 5.5L 200A
  More than 5.5L 250A
• If a load tester is not available, disable the
  engine's ignition of fuel system and crank the
  engine for 15 seconds.
• See pg. 85, Vol. II

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3 - minute charge test

• Determines if the battery is sulfated. Can not
  be performed accurately on maintenance free
  batteries.
• disconnect the (-) cable and properly connect a
  battery charger.
• charge at a rate below 40A, but over 25A for 3
  minutes
• measure charging voltage after 3 minutes, then
  turn off charger
• if the voltage was less than 15.5v, recharge the
  battery
• if the voltage was over 15.5v, replace the battery

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Battery Charging

• When charging a battery the following guidelines
  should be followed.
• well ventilated area
• place a damp cloth over the top to reduce gassing
• disconnect (-) cable
• check electrolyte level, caps or eye
• do not let battery temperature exceeds 120oF
• except for Delco maintenance free batteries, do
  not allow charging voltage to rise above 15.5v
• if a Delco maintenance free battery has been
  discharged for more than a few days, begin
  charging at a high current rate and voltage of at
  least 18v.
• See pg. 182 Vol. II

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Jump Starting Procedure

• 1. connect () to dead battery
• 2. connect () to good battery
• 3. connect (-) to good battery
• 4. connect (-) to engine ground 18 inches or more
  from dead battery
• do not let vehicles touch or boost with more
  than 16 volts
• see pg. 186 Vol. II

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End Lesson Two

• To return the the Automotive Electrical I course
  outline click here.
• To visit the AC Delco battery web site click
  here.
• To visit the Exide battery web site click here.
• To visit the Johnson Controls battery web site
  click here.
• To visit the Ovonic battery web site click here.
• To visit the Black Panther battery web site click
  here.