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B A T T E R Y C H A R G I N G
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M O R N I N G S T A R C O R P O R A T I O N
4.0
4.4.3 Preparation for Equalization
First, confirm that all your loads are rated for the equalization voltage.
Consider that at 0˚C (32˚F) the equalization voltage will reach 16.05V in a 12V
system (64.2V in a 48V system) with a temperature sensor installed.
Disconnect any loads at risk.
If Hydrocaps are used, be sure to remove them before starting an equal-
ization. Replace the Hydrocaps with standard battery cell caps. The Hydro-
caps can get very hot during an equalization. Also, if Hydrocaps are used,
the equalization should be set for manual only (DIP switch #7 is Off).
After the equalization is finished, add distilled water to each cell to replace
gasing losses. Check that the battery plates are covered.
4.4.4 When to Equalize
The ideal frequency of equalizations depends on the battery type (lead-
calcium, lead-antimony, etc.), the depth of discharging, battery age,
temperature, and other factors.
One very broad guide is to equalize flooded batteries every 1 to 3 months
or every 5 to 10 deep discharges. Some batteries, such as the L-16 group,
will need more frequent equalizations.
The difference between the highest cell and lowest cell in a battery can also
indicate the need for an equalization. Either the specific gravity or the cell
voltage can be measured. The battery manufacturer can recommend the
specific gravity or voltage values for your particular battery.
4.4.5 “Equalize” a Sealed Battery?
The standard battery charging table
(see Section 4.2)
shows two sealed
batteries with an “equalization” cycle. This is only a 0.05 volt (12V battery)
boost cycle to level individual cells. This is not an equalization, and will
not vent gas from sealed batteries that require up to 14.4V charging (12V
battery). This “boost” charge for sealed cells allows for adjustability with
the PC software.
Many VRLA batteries, including AGM and gel, have increased charging
requirements up to 14.4V (12V battery). The 0.05V boost shown in the
table (Section 4.2) is less than the accuracy range of most charge controllers.
Alternatively, for these two sealed battery charging programs you may prefer
to consider the PWM absorption stage to be 14.2V and 14.4V (12V battery).
The 14.0, 14.2, and 14.4 volt standard charging programs should be suitable
for most sealed batteries. If not optimum for your battery, the PC software can
be used to adjust these values.
Refer to Section 9.0 for more information about
charging sealed batteries.
4.5 Float
When a battery becomes fully charged, dropping down to the float stage will
provide a very low rate of maintenance charging while reducing the heating
and gasing of a fully charged battery. When the battery is fully recharged,
there can be no more chemical reactions and all the charging current is turned
into heat and gasing.
The purpose of float is to protect the battery from long-term overcharge. From
the PWM absorption stage, charging is dropped to the float voltage. This is
typically 13.4V, and is adjustable with the PC software.
The transition to float is based on the previous 24 hour history. Factors
include the battery voltage, the state of charge the night before, the battery
type, and the PWM duty cycle and stability of the duty cycle. The battery will
be charged for part of the day until the transition to float.
If there are loads for various periods of time during float, the TriStar will cancel
float and return to bulk charge.
Float is temperature compensated.
