Page 81 - Electrician - TT (Volume 1)

ELECTRICIAN - CITS

Grouping of cells

Objectives: At the end of this lesson you shall be able to:
• state the purpose of cells connected in series and parallel
• explain series connections, parallel connection and series-parallel connection of cells.

Grouping of cells: Often an electric circuit requires a voltage or current that a single cell is not capable of
supplying alone. In this case it is necessary to connect groups of cells in various series and parallel arrangements.
Series connections: Cells are connected in series by connecting the positive terminal of one cell to the negative
terminal of the next cell (Fig 1).

Identical cells are connected in series to obtain a higher voltage than is available from a single cell. With this
connection of cells, the output voltage is equal to the sum of the voltages of all the cells. However, the ampere
hour (AH) rating remains equal to that of a single cell.
Example: Suppose three `D’ flashlight cells are connected in series (Fig 2). Each cell has a rating of 1.5 V and
2 AH The voltage and ampere hour rating of this battery would be:

V Battery = V per cell x No.of cells
= (1.5V) (3)
= 4.5 V

AH Battery rating = AH rating of 1 cell
= 2 AH
Parallel connection: Cells are connected in parallel by connecting all the positive terminals together and all the
negative terminals together (Fig 3).

Identical cells are connected in parallel to obtain a higher output current or ampere-hour rating. With this connection
of cells, the output ampere hour rating is equal to the sum of the ampere hour ratings of all the cells. However, the
output voltage remains the same as the voltage of a single cell.
Assignment : Suppose four cells are connected in parallel (Fig 4). Each cell has a rating of 1.5 V and 8 AH. The
voltage and ampere-hour rating of this battery would be:

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CITS : Power - Electrician & Wireman - Lesson 13-19