The following procedure provides a basic field test to check the operation of a  SC2.


Test equipment required: digital multimeter.

Conditions: Sunny or bright overcast if possible


This procedure assumes that the system panels and battery are installed and operational, or at least capable of generating close to the system nominal voltage. Open circuit voltage required from the panels for these tests is at least 11.0 volts for a 12 volt system (22.0 volts for a 24 volt system). Systems should be equipped with disconnects or switches to facilitate connecting and disconnecting components without hazard. If connecting and disconnecting the batteries and solar panel as instructed in this procedure without approved disconnects, care should be taken since arching can occur. On bright days, it may be advisable to partially cover the solar panel to reduce current produced.


WARNING: Most batteries produce hydrogen gas when charging, which is extremely explosive. Avoid making sparks in the vicinity of batteries, and provide adequate battery ventilation.


1) Start with the solar panel and battery connected to the controller, with any loads disconnected or off.

2) If the controller is in the float charge mode ("CHARGE MODE" light off), disconnect the "SOLAR PANEL (+)" and reconnect after waiting a few moments. The controller should go immediately into full charge mode ("CHARGE MODE" light on). If after disconnecting and reconnecting solar panel(+), and battery and solar panel voltage are at least 11 volts (or 22 volts) and the controller stays in float mode, the controller may be defective.

3) Once the controller is in the full charge mode, check continuity through the charging relay. Do this by setting the multi meter to resistance and measuring between "SOLAR PANEL (+)" and "BATTERY(+)" terminals on the controller. Reading should be 0.

4) If the controller is in the full charge mode, or you have just completed step 3, disconnect "BATTERY(+)". The controller should switch to float mode. If the controller does not switch to float mode, and battery is at least 11 volts (or 22 volts) and the solar panel is at least at 15 volts (or 30 volts), the controller may be defective. Controllers rated at 36 and 48 volts will oscillate (rapidly switch on and off).

5) Once in float mode, with the battery (+) disconnected, measure the voltage across "BATTERY (+)" and "BATTERY (-)" on the controller terminal strip. For 12 and 24 volt controllers, this should be about the float voltage. For 36 and 48 volt controllers, this should read 0 and the relay will oscillate (rapidly switch on and off).

6) With battery and solar panel connected, disconnect the "BATTERY VOLTAGE SENSE (+)" (removing the jumper). This should switch the light on.