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TriStar MPPT Operator’s Manual
36
Operation
4.2 Battery Charging Information
4-Stage Charging
The TriStar MPPT 150V has a 4-stage battery charging algorithm for rapid, efficient, and safe
battery charging. Figure 4-2 shows the sequence of the stages.
NIGHT
NIGHT
BULK
CHARGE
ABSORPTION
FLOAT
EQUALIZE
VOL
TAGE
TIME
Figure 4-2. TriStar MPPT 150V Charging Algorithm
Bulk Charge Stage
In Bulk charging stage, the battery is not at 100% state of charge and battery voltage has not yet
charged to the Absorption voltage set-point. The controller will deliver 100% of available solar
power to recharge the battery.
Absorption Stage
When the battery has recharged to the Absorption voltage set-point, constant-voltage regulation
is used to maintain battery voltage at the Absorption set-point. This prevents heating and exces-
sive battery gasing. The battery is allowed to come to full state of charge at the Absorption volt-
age set-point. The green SOC LED will blink once per second during Absorption charging.
The battery must remain in the Absorption charging stage for a cumulative 120 - 150 minutes,
depending on battery type, before transition to the Float stage will occur. However, Absorption
time will be extended by 30 minutes if the battery discharges below 12.5 Volts (25 Volts @24 V,
50 Volts @48 V) the previous night.
The Absorption set-point is temperature compensated if the RTS is connected; otherwise,
voltages set-points are based on the reference of 25
º
C
.
.
Float Stage
After the battery is fully charged in the Absorption stage, the TriStar MPPT 150V reduces the
battery voltage to the Float voltage set-point. 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 float
stage provides a very low rate of maintenance charging while reducing the heating and gasing of
a fully charged battery. The purpose of float is to protect the battery from long-term overcharge.
The green SOC LED will blink once every two (2) seconds during Float charging.
Once in Float stage, loads can continue to draw power from the battery. In the event that the
system load(s) exceed the solar charge current, the controller will no longer be able to maintain
the battery at the Float set-point. Should the battery voltage remain below the Float set-point for
a cumulative 60 minute period, the controller will exit Float stage and return to Bulk charging.
The Float set-point is temperature compensated if the RTS is connected; otherwise, voltages
set-points are based on the reference of 25
º
C
.
Equalize Stage
WARNING: Risk of Explosion
Equalizing vented batteries produces explosive gases. The battery bank must be properly
ventilated.
!
CAUTION: Equipment Damage
Equalization increases the battery voltage to levels that may damage sensitive DC loads. Verify
all system loads are rated for the temperature compensated Equalize voltage before beginning
an Equalization charge.
!
CAUTION: Equipment Damage
Excessive overcharging and gasing too vigorously can damage the battery plates and cause
shedding of active material from the plates. An equalization that is too high or long can be
damaging. Review the requirements for the particular battery being used in your system.
AVERTISSEMENT : Risque d’explosion
Les batteries à évent et compensation produisent des gaz explosifs. Le groupe de batteries doit
être correctement ventilé.
!
PRUDENCE : Endommagement de l’équipement
La compensation augmente la tension des batteries à des niveaux pouvant endommager les
charges sensibles en CC. Vérifiez que toutes les charges du système sont conçues pour la
tension de compensation par température avant de commencer une charge de compensation.
!
PRUDENCE : Endommagement de l’équipement
Une surcharge excessive et un dégagement gazeux trop vigoureux peuvent endommager les
plaques de batteries et provoquer l’élimination du matériau actif des plaques. Une compensation
trop élevée ou trop longue peut provoquer des dégâts. Examinez les exigences pour la batterie
particulière utilisée dans votre système.
