Battery Powered Lights

Battery powered lights are widely used for emergency lighting. The
units are designed to provide sufficient light for the safe evacuation of
the facility in the event of a power failure. Most fixtures will provide
illumination for 30 minutes to two hours. The systems are not designed
to provide enough illumination to allow normal activities to take place
in the building.
Battery powered lights are low maintenance items, requiring little
more than periodic testing. Those units using lead-acid batteries also require that the batteries be topped off with distilled water. The normal
service life for battery-powered lights is 20 years.
The most common defects found in battery-powered lights include
the following:
1. Defective charger. The charger built into the light is designed to
maintain the battery at full capacity. If the charger is not operating
properly, it can under or over charge the unit’s battery. Under
charged batteries will not have sufficient capacity to operate the
light for the required time. Over charged batteries will not reach
their rated service lives. The condition of the charger can be evaluated
by determining the state of the charge on the unit’s battery.
2. Inadequate coverage. Although emergency lighting systems are
not designed to provide uniform lighting levels, they are designed
to provide enough light so that safe egress can be made in the event
of a power outage. To provide enough light, there must be sufficient
fixtures installed to illuminate all means of egress that are to
be used in the event of an emergency. Survey the facility to determine
if there are sufficient fixtures installed and the light that they
produce is sufficient.
3. Insufficient light. Battery powered lights are designed to provide
sufficient illumination for safe egress from an area. While the light
output of a fixture is fairly constant, the illumination that it provides
will vary with the mounting height of the fixture, the location
of objects in the area being illuminated, the color of the wall and
floor finishes, and how large an area that the fixture is serving.
With all other lighting turned off, test the illumination provided by
the battery powered light.
4. Low electrolyte levels. If the fixture uses sealed batteries, skip this
item. As part of the charging process, a portion of the water in the
battery’s electrolyte is lost. Unless this water is replaced on a regular
basis, the batter’s plates may be damaged. High rates of water
loss are an indication that the battery is overcharging or is approaching
the end of its service life.
5. Physical damage. Battery operated emergency lights are subject to
abuse by vandalism or accident. Typical damage includes loose

wiring, broken lamps, improperly aimed lamps, dented or broken
cases, and loose wall or ceiling mounts. Minor damage to the fixture
can be repaired. More extensive damage may require that the
fixture be replaced.
6. Short operating times. Battery powered emergency lights are designed
to provide light for a set period of time. As the batteries age,
their storage capacity decreases, reducing the amount of time that
they can provide illumination. Test the battery operated light and
record the time that it produces light. Shorter operating times are
an indication that either the batteries are not being properly
charged, or that they are approaching the end of their service lives.