User manual

Figure 10. Block Diagram of a Solar System
In actual use in indoor applications (5
0
C to 40
0
C or 41
0
F to
104
0
F), it is not necessary to provide the charger with a
temperature compensation function, but it is desirable to set
the voltage at the value shown in Figure 8 which
corresponds most closely to the average ambient temperature
of the battery during service.
Any temperature compensation sensor must sense only the
temperature of the battery. Therefore, consideration should
be given to isolating the battery and temperature sensor from
other heat generating components of a system.
 Charging Efficiency
The charging efficiency varies depending upon the state of
charge of the battery, temperature, and charging rate. As
shown in Figure 9, Genesis
®
NP batteries exhibit very high
charging efficiency, even when charged at low charging rates.
It is interesting to note that the charging efficiency of Genesis
NP sealed lead-acid batteries is superior to that of other
batteries at relatively low charge rates
.

Solar Powered Charging
A battery is an indispensable component of any solar
powered system designed for demand-energy use. Since
solar cells have inherent constant voltage characteristics,
Genesis NP batteries can be charged directly from the solar
array using a simple diode regulated circuit as shown in
Figure 10.
In designing a solar system, consideration should be given to
the fact that, in addition to normal periods of darkness,
weather conditions may be such that solar energy is limited,
or virtually unavailable for long periods of time. In extreme
cases, a system may have to operate for 10 to 20 days with
little or no power available for charging. Therefore, when
selecting the correct battery for a solar application, the
capacity should be determined based upon maximum load
conditions for the maximum period of time the system may
be expected to be without adequate solar input.
In many instances the battery capacity will be 10 to 50 times
greater than the maximum output of the solar panels. Under
these circumstances, the maximum output of the solar array
should be dedicated to charging the battery with no load-
sharing or intervening control devices of any kind.
Naturally, in cases where the output of the solar array exceeds
the capacity of the battery, and weather conditions are such
that the potential for overcharging the battery exists,
appropriate regulated charging circuitry between the solar
panels and the battery is recommended
.
Remote site, or other outdoor applications for solar systems
are commonplace. When designing a solar system for this
class of application, a great deal of consideration must be
given to environmental conditions. For example, enclosures
which may be used to house batteries and other equipment
may be subject to extremely high internal temperatures when
exposed to direct sunlight. Under those conditions, insulating
the enclosure and/or treating the surface of the enclosure with
a highly reflective, heat resistive material is recommended.In
general, when designing a solar system, consultation with the
solar panel manufacturer and battery manufacturer is
recommended
.
12 www.enersys.com
Publication No: US-NP-AM-003 • January 2011
Figure 8. Relationship Between Charging Voltage and Temperature
Figure 9. Charging Efficiency
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