41
TriStar MPPT Operator’s Manual
40
Operation
The TriStar MPPT 150V provides seven (7) standard battery charging settings that are selectable
with the settings DIP switches (see Figure 4.1 above). These standard charging settings are
suitable for lead-acid batteries ranging from sealed (gel, AGM, maintenance-free) to Flooded and
L-16 cells. In addition, an 8th charging setting provides for custom set-points using MSView
TM
PC
software.
Shared Settings
Value
Units
Absorption Extension Voltage
12.50
Volts
Absorption Extension Time
Absorption Time + 30
minutes
Float Exit Timeout
60
minutes
Float Cancel Voltage
12.30
Volts
Equalize Timeout
Equalize Time + 60
minutes
Temperature Compensation Coefficient*
- 5
millivolts /
°C / cell
* 25°C reference
Table 4-2. Battery settings that are shared between all battery types
The shared settings in Table 4-2 above are common to all battery types. The following
illustrations graphically explain the shared settings.
Absorption Extension
1:00
2:00
3:00
4:00
5:00
6:00
12.50 V
Bulk
Extended
Absorption
Float
Absorption
Absorption Extension Voltage
time (hrs)
Figure 4-3. Absorption extension charging profile.
If battery voltage discharges below 12.50 Volts (25.00 Volts @ 24 V, 50 Volts @ 48 V) 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
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 larger than the charge current, causing battery voltage to drop below Float voltage for
60 minutes. After the load runs for 60 minutes, 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
12.30 V
Bulk
Absorption
Float Cancel Voltage
time (hrs)
Float cancelled this charge cycle
Figure 4-5. Float cancelled charging profile
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.
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
