Question 1
-
(a) Two 12 V, 45 AH lead-acid batteries were connected in series for a practical session in an Auto Electrical Works (AEW) workshop.
- State the meaning of 45 AH in relation to battery capacity.
- Draw a circuit diagram for the connection.
- Calculate the total:
(I) voltage;
(II) capacity.
(b) Table 1 contains some common faults in a lead-acid battery.
Table 1
S/NFault
Symptom of fault
Remedy
I
Lagging cells
II
Corrosion of terminals
III
Short circuit
IV
Sulphation of plate
Complete Table 1 by stating one symptom of fault and one remedy for each fault listed.
Observation
The expected responses were:
- (i) The battery delivers a current of 1 A steadily for 45 hours.
(ii) Diagram of two batteries connected in series
(II) Total capacity remains same for batteries connected in series.
Hence, total capacity = 45 AH
- Table 1
S/N |
Fault |
Symptom of fault |
Remedy |
I |
Lagging cells |
|
|
II |
Corrosion of terminals |
|
|
III |
Short circuit |
|
|
IV |
Sulphation of plate |
|
|
Question 1 required candidates to show understanding of basic terminology and total output of a combination of batteries. More so, other part of the question required candidates to show familiarity with some common faults in a lead acid battery. The Chief Examiner reported that majority of the candidates that attempted question 1 could neither show understanding of the effect of combination batteries nor state the symptoms and expected remedies to common battery faults given.