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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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