Operation
ProStar MPPT Operator’s Manual
45
44
4.0
If battery voltage discharges below 12.50 volts (25.00 volts
@ 24V) the previous night, Absorption charging will be
extended on the next charge cycle as shown in figure 4-3
above. 30 minutes will be added to the normal Absorption
duration.
Float Time-out
1:00
2:00
3:00
4:00
5:00
6:00
Float V
Bulk
Float
Sub-
Float
Absorption
Absorption
60 mins.
below Float
time (hrs)
Bulk
Figure 4-4. Float Exit Time-out Charging Profile
After entering Float stage, the controller will only exit Float
if the battery voltage remains below Float voltage for 60
cumulative minutes. In figure 4-4, a system load turns on at
4:00 hrs when the controller is in Float stage, runs for one
hour, and turns off at 5:00 hrs. The load current draw is larg-
er than the charge current, causing battery voltage to drop
below Float voltage for 60 minutes. After the load turns off,
the controller returns to Bulk charging and then Absorption
stage once again. In this example, a load runs continuously
for 60 min. However, because the Float exit timer is cumula-
tive, multiple momentary load events that pull the battery
voltage below Float voltage for a combined 60 minutes
duration will also force an exit from Float stage.
Float Cancel Voltage
Figure 4.5. Float Cancellation Charging Profile
1:00
2:00
3:00
4:00
5:00
6:00
12.10 V
Bulk
Absorption
Float Cancel Voltage
time (hrs)
Float cancelled this charge cycle
If the battery bank discharges below 12.10 volts (24.20
volts @ 24 V) the previous night, Float charging stage will
be cancelled for the next charge cycle. Figure 4-5 above,
illustrates this concept. At 0:00 hrs (dawn), battery voltage
is below the Float Cancel threshold voltage. The diagram
shows where Float stage would have occurred if Float was
not canceled.
