TriStar Manual

37TriStar MPPT Operator’s Manual
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prole
After entering Float stage, the controller will only exit Float if the battery voltage remains below
Floatvoltagefor60cumulativeminutes.Ingure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 larger than the charge current, causing battery voltage to drop below Float voltage for 60 min-
utes. 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 cumulative, 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
1:00 2:00 3:00 4:00 5:00 6:00
11.50 V
Bulk
Absorption
Float Cancel Voltage
time (hrs)
Float cancelled this charge cycle
Figure4-5.Floatcancelledchargingprole
If the battery bank discharges below 12.30 Volts (24.60 Volts @ 24 V, 49.20 Volts @ 48 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 cancelled.