Batteries

							Batteries
Mr. Conrado
                          Batteries
• A battery stores electrical
  energy in chemical form.
• Battery current is produced by a
  chemical reaction between the
  active materials of the battery
  plates and the sulfuric acid in
  the electrolyte.
• The battery is a voltage
  stabilizer for the system and
  acts as a reservoir of power.
              Battery Basic Theory
• All Batteries operate on the
  principle of dissimilar metals -
  2 different metals (plates) in the
  presence of a liquid
  (electrolyte) make a voltage.
• Battery chemistry determines
  cell capacity
• Battery size determines amp
  capacity.
• Batteries contain voltage - not
  Amperage.
For good operation a battery must...

• Supply current for starting.
• Supply current when demand exceeds the
  charging system output.
• Stabilize the voltage in the system during
  operation.
              Battery Construction
• The basic parts consist of
  positive and negative plates
  encased in a plastic or hard
  rubber case and submerged in
  electrolyte.
    – Negative plates have a lead
      surface, which is gray in color.
    – Positive plate have a lead
      peroxide surface which is
      brown in color.
    – The negative and positive
      plates are connected in plate
      groups.
             Battery Construction
• Each plate in the group is kept
  apart by porous separators to
  allow the flow of electrolyte
  around the plates.
• The complete assembly is
  called an element. Elements are
  connected in series to increase
  voltage.
• Cells are separated from each
  other so there is no flow of
  electrolyte between them.
• Each cell will produce about 2.1
  - 2.2 volts.
                Battery Electrolyte
• Electrolyte is a concentrated
  solution of sulfuric acid in
  water.
• It has a specific gravity of 1.270
  at 80deg. F.
• The solution is about 36%
  sulfuric acid and 64% water.
• Battery water - it is best to use
  distilled water to prevent
  impurities in the battery thus
  reducing the life and
  performance of the battery.
      Battery Terminals and Caps
• Batteries have negative and
  positive posts or terminals.
• The positive post is larger than
  the negative to help prevent the
  battery from being connected in
  reverse polarity.
• Vent caps are located in each
  cell cover.
• Vent caps cover access holes
  through which the electrolyte
  level can be checked and water
  added. The vents provide an
  escape of gasses during
  charging.
                   Battery Potential
• Each cell in a battery has a
  potential of about 2 volts. Six
  volt batteries have three cells in
  series, while 12 volt batteries
  have 6 cells in series.
• For higher voltages,
  combination of batteries are
  used.
            How a Battery Works
• The battery produces current by
  a chemical reaction between the
  active materials of the unlike
  plates and the sulfuric acid.
  During this process the battery
  is discharging. After almost all
  of the materials have reacted
  the battery is discharged.
• Battery current depends on the
  size and number of its plates.
                     Battery Cycles
• Batteries have two cycles
    – Discharging
    – Charging
• Discharging cycle - When a
  battery discharges lead sulfate
  forms on both plates making the
  two plates similar. This
  accounts for less cell voltage
  because the process depends on
  dissimilar metals. In addition
  during the discharging process
  more water is formed in the
  electrolyte. The acid never
  leaves the battery it forms in the
  lead sulfite. Therefore never
  add more acid to a battery
                    Battery Cycles
• Charging Cycle - in essence the
  discharge process is reversed in
  the charging process.
• The sulfuric acid leaves the
  plates and goes back into
  suspension in the electrolyte.
     Variation of terminal voltage
• Battery voltage in not constant.
  The main factors affecting
  voltage is temperature and
  operating cycle.
• Temperature affects the
  chemical reactions. At lower
  temps the reactions are slower
  thus reducing voltage and
  efficiency.
• A Battery is 100% efficient at
  81 deg. F and 30% efficient at -
  22 deg F.
                 Types of batteries
• There are two types of batteries
  - conventional and maintenance
  free.
• Conventional batteries can be
  dry or wet charged. A dry
  charged battery contains no
  electrolyte but is fully charged.
  Once activated with electrolyte
  it becomes wet charged. Dry
  charged batteries if maintianed
  correctly will not loose charge
  on the rack.
                 Types of batteries
• Wet charged batteries are fully
  charged and contain electrolyte.
• During storage a slow reaction
  between the plates and
  electrolytes takes place
  discharging the battery.
• A fully charged battery stored
  at 103 deg. F will fully
  discharge in 90 days.
                 Types of batteries
• Maintenance free batteries are
  the same as conventional
  batteries minus the vent caps so
  the electrolyte is sealed inside
  the battery.
• Often an indicator is built into
  the battery. The indicator has a
  small green ball that floats
  when the specific gravity is
  1.225 or higher.
                Types of batteries
• Maintenance free batteries
  produce the same gasses during
  charging and discharging but
  the gasses are contained in a
  special chamber that condenses
  them and returns them to the
  electrolyte.
• Also M-F battery plates are
  sealed in envelopes to contain
  sediment during normal wear,
  conventional batteries leave
  room at the bottom of the case
  for sediment to settle.
                 Types of batteries
• Deep cycle batteries - Also a        • Batteries are rated in three areas
  lead acid battery but is specially     - Cold Cranking Amps,
  constructed for applications           Cranking performance, and
  where there may not be a               reserve capacity.
  charging circuit in the system,          – Cold Cranking Amps - the
  or used when the charging                  basic job of the battery is to
  system is not being used (ie a             start the engine. Since it is
  motor-home). The deep cycle                harder to start a cold engine
  has denser electrolyte and                 and a battery is less efficient
                                             when cold this is a good rating
  thicker plates. These type of
                                             for batteries
  batteries can be discharged and
                                           – Definition - A fully charged
  recharged several times without
                                             battery can continually crank
  harm.                                      for 30 seconds and maintain
                                             1.2 volts per cell.
                Types of batteries
• Cranking performance - The        • Reserve Capacity - The ability
  discharge rate in amps which a      of a battery to sustain a
  new fully charge battery at 32      minimum machine electrical
  deg. F can continuously deliver     load in the case of a charging
  for 30 seconds and maintain a       system failure.
  voltage of 1.2 volts per cell.    • Group Size - This is the
                                      physical dimension of the
                                      batteries and is industry
                                      standardized
   Lab

Battery Lab 1
                    Battery Charging
• When a battery’s state of charge
  is low, it should be recharged.
• There are two classifications of
  battery chargers, constant
  current and constant voltage.
    – Constant current – Supplies a
      constant or set amount of
      current to the battery. Charge
      at a rate of 1 amp per positive
      plate per cell. (ie; if 5 positive
      plates per cell charge at 5
      amps.) Most batteries which
      are charged with a constant
      current charger will take 5 to 6
      amps.
             Battery Charging
– Constant voltage – Supplies
  battery with a constant
  voltage during charging.
  (ie; 15 volts for a 12 volt
  battery). When the battery
  is low this type of charger
  will supply a fairly large
  amount of amperage but as
  the battery builds up charge
  the current supply gradually
  tapers off until almost
  nothing.
 Charging Conventional Batteries
• If possible slow charging is
  preferable because the battery is
  more thoroughly charged.
  However a proper slow charge
  takes 24 to 48 hours. A slow
  charge is defined as a rate of 10
  amps or less.
• The batteries specific gravity
  should be checked twice a day.
  If the battery reaches a specific
  gravity of 1.275 remove the
  charger.
                      Fast Charging
• Fast chargers
    – will give a battery a high
      charge rate for a short time.
    – are generally portable
      allowing for easier in machine
      charging.
    – Usually can charge only one
      battery at a time.
    – Many modern fast charges can
      also slow charge as well.
  Precautions when fast charging
• Never allow the batteries
  electrolyte to exceed 125 deg.
  F.
• During fast charging the
  sediment is stirred up in the
  electrolyte and can lodge
  between plates shorting them.
  Sediment will be noticeable by
  discoloration of the electrolyte.
  If this happens reduce the
  charge rate.
       Correct Charging Practices
• Before connecting the charger       • Charging time
  be sure that the battery tops are      – Maintenance free batteries are
  clean and the electrolyte is at          charged at lower rates for
  the correct level (conventional).        longer periods.
• Be sure charger is off before          – Never fast charge for longer
  connecting and disconnecting             than one hour.
  the charger leads to the battery.
• Be sure to connect charger
  leads in the correct polarity.
• Check the charger settings
  before tuning it on.
                     Jump Starting
• Before jump starting be sure all
  electrical accessories are off.
• Observe proper battery voltage
  when jump starting. (12v to
  12v, 24v to 24v etc.) If you do
  not the battery could spark and
  explode.
• Be sure to observe proper
  polarity when connecting
  jumper cables.
                       Jump Starting
• Be sure to connect cable in the
  proper order.
    – Positive of dead battery first.
    – Positive of booster battery
      second.
    – Negative terminal of booster
      battery.
    – Connect negative lead at dead
      battery end to a good ground
      on the equipment.
• Remove in reverse order.
                    Battery Testing
• In order to determine what is
  wrong with a battery you must
  perform two tests.
    – Specific Gravity Test
    – Load Test
• Specific Gravity Test – Specific
  Gravity is the weight of the
  battery electrolyte compared to
  water. When performing this
  test you are determining the
  state of charge based on the
  percentage of acid to water. The
  state of electrolyte varies
  directly with the state of
  charge. Specific Gravity is done
  using a Hydrometer.
                   Battery Testing
• Hydrometers are calibrated to
  measure at 80°. F. You must
  compensate for varying
  temperatures.
    – Add 0.004 hydrometer points
      for each 10° F above 80°.
    – Subtract 0.004 hydrometer
      points for each. 10°
• Specific Gravity will not be
  correct if water was recently
  added. Charge the battery and
  re-test.
                   Specific Gravity
• Electrolyte should be clear.
• If the battery tests below 1.250,
  charge the battery and retest.
• The amount of variation
  between cells should be
  between 30 to 50 points.
            Load Testing Batteries
• A load test is the best indication
  of a batteries condition.
• A load test can be performed if
  the batteries state of charge is
  75% or better. If below charge
  then test.
• If a battery maintains 9.6 volts
  or more during a load test it is
  considered good.
           Load Testing Batteries
• Load Test Procedures
   – Place control knob in off
     position
   – connect leads observing proper
     polarity.
   – Turn on the control knob until
     the ammeter reads one half the
     cold cranking rate of the
     battery.
   – Maintain the load for 15
     seconds.
   – Note the reading of the
     voltmeter and turn off tester.
   – If the battery maintained a
     minimum of 9.6 volts the
     battery is good.
             Safety and Clean-up
• Lead Acid Batteries produce      • To avoid arcing and melted
  hydrogen and oxygen when           tools always disconnect
  over-charged.                      negative cable first and
• Hydrogen + Oxygen + Flame =        reconnect last.
  Explosion.
• Use 8 tablespoons of baking
  soda in one gallon of water to
  neutralize battery acid.
• Never add acid to cells -
  distilled water only.
     Video

Kubota Battery Pro
              Demonstrations
•   Battery voltage test
•   Post leakage test
•   battery draw test
•   Hydrometer test
•   Headlight test
•   Load test
•   Battery charging
Lab