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                                                                                   ELECTRICIAN - CITS



           EXERCISE 18 : To charge lead acid battery by constant

                                     voltage & constant current method

           Objectives

           At the end of this exercise you shall be able to
           •  measure the voltage & specific gravity of lead acid battery
           •  charge the battery by constant voltage method
           •  charge the battery by constant current method.

           Requirements

           Tools/Equipments                                    •  Hydro meter                      - 1 No.
           •  Combination plier (165mm, insulated)  - 1 No.    •  Digital multi meter (3  digit)      - 1 No.
                                                                                     1/2
           •  Neon tester (75 mm, insulated)    - 1 No.        Materials
           •  Electrician Knife  (Insulated)       - 1 No.
           •  Spanner set (7 to 15mm)           - 1 Set.       •  Connecting wire with crocodile clip
                                                                                                 - 1 set.
                                                                  (4.0 sq.mm)
           •  Screw driver (150mm, insulated)   - 1 No.        •  Distilled water                - 2 litre.
           •  Lead acid battery (12 V, 100 Ah)   - 1 No.       •  Petroleum jelly                - As reqd.
           •  Battery charger (12-24 V, 15 A)    - 1 No.       •  Sand paper                     - As reqd.


            Procedure

           TASK 1 : Charge the battery by constant voltage charging method
           1  Draw the circuit diagram of constant voltage method of battery charging.
           2  Clean the battery with wet cotton cloth & clean its terminals with sand paper.
           3  Uncap the vent plugs, Check the specific gravity of electrolyte with hydrometer.

           4  Connect the battery terminals to battery charger with proper polarity.
           5  Set the charging voltage of 13.5 V in battery charger and switch ON the unit. (Charging voltage / value should
              be as per manufactures instruction)

           6  Record charging voltage & battery voltage and wait until battery gets fully charged.
           7  Disconnect the battery after it is fully charged, and measure the battery voltage.
           8  Fix the caps of vent plugs and test the battery by connecting load.




           TASK 2 : Charge the battery by constant current charging method
           1  Draw the circuit diagram of constant current method of battery charging.

           2.  Uncap the vent plugs, Check the specific gravity of electrolyte with hydrometer.
           3  Connect the battery terminals to battery charger with proper polarity.
           4  Set the charging current at low rate in battery charger and switch ON the unit. (Charging / current value should
              be as per manufactures instruction)
           5  Record charging current & voltage, and wait until battery gets fully charged.
           6  Disconnect the battery after it is fully charged, and measure the battery voltage.
           7  Fix the caps of vent plugs and test the battery by connecting load.






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