The batteries contained within these units should replaced about
every years, recommended the manufacturer.
A record should kept each item equipment and the date each
test qualified responsible person. may necessary produce
the record evidence satisfactory compliance with statutory legislation
to duly authorized person.61
The construction lead-acid battery. Once the active chemicals are
exhausted, the cell must discarded.61 shows the construction lead-acid battery.
Secondary cells
A secondary cell has the advantage being rechargeable. the cell con-
nected suitable electrical sup-
ply, electrical energy stored the
plates the cell chemical energy.
Definition
A secondary cell has the advantage of
being rechargeable. Figure 14. They have long shelf life and leakproof
construction, and are used watches and hearing aids. the cell is
connected suitable electrical supply, electrical energy stored the
plates the cell chemical energy.
A lead-acid cell secondary cell.
Definition
A primary cell cannot recharged. When the cell connected load,
the chemical energy converted electrical energy.
.35V, and can have very large
capacity small physical size.
Once the active chemicals are
exhausted, the cell must discarded.
Negative
connecting bar
Positive
connecting bar
All plates
deeply
ribbed Negative plate
Separator
Positive plate
FIGURE 14.
Mercury primary cells have emf 1. After testing, the
emergency system must carefully restored its normal operative state.
Primary cells
A primary cell cannot recharged.5V.
Self-contained units are suitable for small installations about 12
units. Each cell delivers about 2V, and when
six cells are connected series 12V battery formed the type used on
motor vehicles. Primary cells, the form Leclanche cells, are used extensively por-
table power sources for radios and torches and have emf 1. Thus, supply can
be provided connecting four cells series. Larger
voltages are achieved connecting cells series.Basic Electrical Installation Work
342
The British Standard recommends that the full load should carried by
the emergency supply for least every months
