Auto Electrical Works Paper 3, WASSCE (SC), 2017

Question 3

 

AIM: To test the specific gravity and capacity of a 12V battery.
You are provided with a serviceable 12V lead-acid battery.
(a) Remove the battery caps and observe the electrolyte level.
(b) Record your observation in step (a) in the spaces provided as either below, normal or excess.
(c) Check the specific gravity of the electrolyte of each cell and record your readings in Table 3.
(d) Comment on your readings.
(e) Measure the capacity of the battery and record the reading in the spaces provided.
(f) State two precautions taken in carrying out the above listed activities.
(g) State five steps that would be taken to install a battery into a motor vehicle.


Table 3

 


Cell

Specific gravity

1

 

2

 

3

 

4

 

5

 

6

 

 

 

Observation

 

  (b) Below cell level                                                                
   (c)                                              

          Table 3


Cell

Specific gravity

1

1.000 ± 0.005

2

1.000 ± 0.005

3

1.000 ± 0.005

4

1.000 ± 0.005

5

1.000 ± 0.005

6

1.000 ± 0.005

 

                                                                                           
(d) The specific gravity shows that electrolyte level is below normal                      
(e) 65 AH                                                                                                                   
(f) Precautions in carrying out experiment

  • I ensured the use of personal protective devices such as rubber gloves.
  • I avoided error due to parallax in hydrometer reading
  • I avoided contact with  electrolyte                                                                  

    (g) Steps to install a battery into a motor vehicle

  • Place battery in position
  • Clamp the battery
  • Connect the negative terminal
  • Connect the positive terminal
  • Apply grease