Auto Electrical Works Paper 2, WASSCE (SC), 2017

Question 1

 

  1. With the aid of a sketch, show the connection of a six cell battery in series to three lamps.
  1. List six components of a lead-acid battery.

(c) State the condition of a lead-acid battery cell when the battery is:
(i) charged;
(ii) discharged.
(d) State three safety precautions that should be taken when mixing electrolyte.

 

Observation

           The expected answers were;

  • Sketch showing the connection of a six-cell battery in series connection to three lamps

   

   

 

Components of a lead-acid battery

  • Container/protective casing
  • Separators/cell divider
  • Electrolyte/dilute sulphuric acid
  • Plates
  • Grids
  • Cell covers/plastic cover
  • Cell connectors
  • Cells
  • Positive terminal/post
  • Negative terminal/post
  • Sealing components
  • Indicator
  • Vent plug

(c) (i) Condition of lead-acid battery cell when charged

  • Positive plate becomes lead peroxide and negative plate becomes spongy lead.
  • Cell produces the required voltage.

                                                             
(ii) Condition of lead-acid battery cell when discharged

  • Both positive and negative plates become lead-sulphate/sulphation of cells/white crystal material deposit on cells.
  •  Cell does not produce the required voltage.  

                                                                        

(d) Safety precautions that should be taken when mixing electrolytes.

  • Always add acid to water and not the reverse.
  • Electrolytes should be mixed in non-corrosive container.
  • Electrolytes should be mixed in a well ventilated environment.
  • No naked light in a mixing room should be allowed.
  • Ensure the use of leather aprons when mixing electrolytes.
  • Ensure the use of rubber hand gloves.
  • Wear safety goggles.
  • Wear safety boots.

                                             
To obtain maximum mark in the (a) part, candidates were required to draw: correct symbol of 6 cells in series; correct symbol of 3 lamps either in series or in parallel; connecting wires. Majority of the candidates that attempted question one responded quite satisfactorily.