Morningstar TriStar TS-MPPT-30, Инструкция по установке и эксплуатации

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39 TriStar MPPT Operator’s Manual
Temperature Compensation
All charging settings are based on 25°C (77°F). If the battery temperature varies by 5°C, the
charging setting will change by 0.15 Volts for a 12 Volt battery. This is a substantial change in
the charging of the battery, and the use of the Remote Temperature Sensor (RTS) is recom-
mended to adjust charging to the actual battery temperature.
The need for temperature compensation depends on the temperature variations, battery type,
how the system is used, and other factors. If the battery appears to be gassing too much or not
charging enough, the RTS can be added at any time after the system has been installed. See
Section 2.3 - Step 4 for installation instructions.
Battery Sense
Voltage drops are unavoidable in power cables that carry current, including the TriStar MPPT
battery cables. If Battery Sense wires are not used, the controller must use the voltage reading
at the battery power terminals for regulation. Due to voltage drops in the battery cables, the bat-
tery power connection voltage will be higher than the actual battery bank voltage while charging
the battery.
Two sense wires, sized from 1.0 to 0.25 mm 2 (16 to 24 AWG), can be used for battery voltage
sense. Because these wires carry no current, the voltage at the TriStar will be identical to the
battery voltage. A 2-position terminal is used for the battery sense connection.
Generally accepted wiring practice is to limit voltage drops between the charger and the battery
to 2%. Even properly sized wiring with 2% drop can result in a 0.29 Volt drop for 14.4V charg-
ing (or 1.15 Volt for a 48 Volt nominal system). Voltage drops will cause some undercharging of
the battery. The controller will begin Absorption or limit equalization at a lower battery voltage
because the controller measures a higher voltage at the controller’s terminals than is the actual
battery voltage. For example, if the controller is programmed to start Absorption at 14.4V, when
the controller “sees” 14.4V at its battery terminals, the true battery voltage would only be 14.1V if
there is a 0.3V drop between the controller and battery.
Note that the battery sense wires will not power the controller, and the sense wires will not com-
pensate for losses in the power wires between the controller and the battery. The battery sense
wires are used to improve the accuracy of the battery charging.
See Section 3.2 - Step 7 for instructions on how to connect the battery sense wires.