Absorbing
This stage limits the amount of power going to the battery -- the voltage is
held constant. The absorb charge will continue for the duration of the bulk
cycle or until the 2 hours (default) absorb time limit is reached. For example,
if a bulk charge takes 1 hour to reach the absorb voltage set point then the
absorb charge will continue for 1 hour as well. However, if a bulk charge takes
3 hours to reach the absorb voltage set point then the absorb charge will last
for 2 hours only. A bulk charge will be re-initiated if the battery voltage is not
sustained at the absorb voltage set point.
Float
This stage reduces the charging voltage to prevent overcharging of the
batteries. A float charge follows after the absorb charge is completed. The
MPPT will not re-initiate another bulk charge if the float voltage set point
is not sustained, however, it will continue to charge the battery until the
float voltage set point is achieved. Note: A bulk charge can be initiated if the
battery voltage falls below the float voltage set point if the re-bulk (ReBV)
voltage option is set.
Understanding the various modes
The modes of operation will change occasionally during the day based on
the turbine's output and battery system state of charge. The MPPT operating
modes are displayed through the LED.
Sleeping
Happens when the wind turbine’s voltage is less than the battery voltage or
charger current is below the minimum cutoff (Low cutoff) current. This may
also appear briefly during the day when the MPPT is transitioning between
certain states, and because of other conditions.
Absorb
There is an external DC source (wind generator/hydro) keeping the battery at
or above the absorb set point.
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