TriStar MPPT 600V Installation & Operation Manual

41TriStar MPPT 600V Operator’s Manual
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denedastimespentattheequalize
set-point.Ifthereisinsufcientchargecurrenttoreachtheequalizationvoltage,theequalization
will terminate after an additional 60 minutes to avoid over gassing or heating the battery. If the
battery requires more time in equalization, an equalize can be requested using the TriStar Meter
or pushbutton to continue for one or more additional equalization cycles.
The Equalize set-point is temperature compensated if the RTS is connected.
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ooded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specicgravityorthecellvoltagecanbemeasured.Thebattery
manufacturercanrecommendthespecicgravityorvoltagevaluesforyourparticularbattery.
Why Equalize?
Routine equalization cycles are often vital to the performance and life of a battery - particularly in
a solar system. During battery discharge, sulfuric acid is consumed and soft lead sulfate crys-
tals 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difculttoconvertbacktosoftactivematerials.
Sulfation from chronic undercharging of the battery 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 bat-
tery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.
Preparation for Equalization
First,conrmthatallofthesystemloadsareratedfortheequalizationvoltage.Considerthatat
0°C (32°F) the equalization voltage will reach 67.00 Volts for L-16 batteries with a temperature
sensor installed. Disconnect any loads at risk of damage due to the high input voltage.
IfHydrocapsareused,besuretoremovethembeforestartinganequalization.Replacethe
Hydrocapswithstandardbatterycellcaps.TheHydrocapscangetveryhotduringanequaliza-
tion.Also,ifHydrocapsareused,theequalizationshouldbesetformanualonly(DIPswitch#7
is Off).