Auto Electrical Works Paper 3, May/June 2015

 Menu General Comments Weakness/Remedies Candidate's Strength

Question 3

(a) Copy Table 3 into your answer booklet

Table 3

 Parameter Specific gravity Temperature         (OC) No load voltage   (V) Load voltage     (V) Ampere – Hour rating    (AH) Reading

(b) Measure and record in Table 3 the specific gravity and temperature of the electrolyte.

(c) Measure and record in Table 3 the voltage across battery terminals.

(d) Measure the voltage across the battery terminals with a high - rate discharge tester and record the reading in Table 3.

(e) Based on the specific gravity and temperatures obtained in Table 3, comment on the state of the battery.

(f) Evaluate no load – load voltage.

(g) Comment on the value obtained in (f)

(h) Read and record the in Table 3 the ampere-hour rating of the battery given to you.

Observation

The expected answers were;

(a) Copying of the Table

Table 3

 Parameter Specific gravity Temperature           (OC) No load voltage     (V) Load voltage     (V) Ampere-Hour rating    (V) Reading Between 1.275 – 1.300 About 21 OC 12V – 13V 10V-12V 60AH

(b) Specific gravity is between 1.275 – 1.300

(c) No load voltage is between 12V – 13V

(d) Load voltage is between 10V – 12V

(e) Comment on the reading; the battery is fully charged

(f) No load voltage – load voltage (12V – 10V =2V or 13V – 12V =1V) Accept other values within the range.

(g) When battery is subjected to a load, ( depending on the quantity of load) the voltage across the terminal drops significantly small

(h) 60AH

The candidates were required to measure the specific gravity of 60AH battery, temperature of the battery, load and no load terminal voltage, comment on the charge state of the battery.

Candidates' performance was reported to be averagely good.