Morningstar ProStar MPPT Manual

Operation
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battery voltage above the standard absorption voltage so
that the electrolyte gases. The green SOC LED will blink
rapidly two (2) times per second during equalization
charging. The duration of the equalize charge is determined
by the selected battery type. See table 4-1 in this section for
more details. The Equalization Time is defined as time spent
at the equalization set-point. If there is insufficient charge
current to reach the equalization voltage, the equalization
will terminate after an additional 60 minutes to avoid over
gasing or heating the battery. If the battery requires more
time in equalization, an equalize can be requested using the
TriStar Meter or push-button to continue for one or more
additional equalization cycles.
The Equalization set-point is temperature compensated if
the RTS is connected.
Why Equalize?
Routine equalization cycles are often vital to the perfor-
mance and life of a battery - particularly in a solar system.
During battery discharge, sulfuric acid is consumed and
soft lead sulfate crystals form on the plates. If the battery
remains in a partially discharged condition, the soft crystals
will turn into hard crystals over time. This process, called
“lead sulfation”, causes the crystals to become harder
over time and more difficult to convert back to soft active
materials. Sulfation from chronic undercharging of the bat-
tery is the leading cause of battery failures in solar systems.
In addition to reducing the battery capacity, sulfate build-up
is the most common cause of buckling plates and cracked
grids. Deep cycle batteries are particularly susceptible to
lead sulfation.
Normal charging of the battery can convert the sulfate back
to the soft active material if the battery is fully recharged.
However, a solar battery is seldom completely recharged, so
the soft lead sulfate crystals harden over a period of time.
Only a long controlled overcharge, or equalization, at a
higher voltage can reverse the hardening of sulfate crystals.