Test equipment required: Digital Multimeter

Conditions: Sunny or bright overcast if possible


This procedure assumes that the solar panels are installed and operational and capable of producing at least 17.5 volts open circuit (for a 12 volt system). Proportionately higher for higher voltage systems. Systems should be equipped with disconnects or switches to facilitate connecting and disconnecting the batteries and solar panel as described in this procedure. If performing this procedure without approved disconnects, care should be taken since arcing may occur. On bright days it may be advisable to partially cover the solar panel to reduce the 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.


All measurements described in this procedure should be made at the controller terminals.


1) Disconnect Load(+), Array(+), Battery(+), and Battery Sense(+)(jumper or wire) from the controller. Secure each wire away from any possible contact with other wires, metal chassis, enclosures etc.

2) Measure the resistance between the Battery(+) and Solar Panel(+) terminals on the controller. It should be open (more than 10M ohm). Turn on load circuit breaker and measure the resistance between Load(+) and Battery(+). It should be less than 1 ohm. Turn off load circuit breaker and re-measure. It should be open.

3) Reconnect the solar panel to the controller. (On 36 volt or 48 volt chargers, briefly connect a jumper wire between Solar Panel(+) and Battery(+). When the charge light comes on, remove the jumper).The charge light should go on, and after a few moments the load disconnected light should come on.

4) Measure the voltage between Solar Panel(+) and Solar Panel(-). It must be at least 17.5 volts for a 12 volt system (proportionately higher for higher voltage systems).

5) Measure the voltage between Battery(+) and Battery(-). It should be the same as the voltage measured in step 4.

6) Turn on load circuit breaker and measure the voltage between Load(+) and Load(-). It should be zero.

7) For 12 volt or 24 volt chargers, go to step 8. For 36 volt or 48 volt chargers, install a jumper wire between Battery(+) and Solar Panel(+) then go to step 8.

8) Install a jumper between Battery(+) and Battery Sense(+). The charge mode light should turn off. Move the LVD switch to manual reset and observe that the load disconnected light turns off. Note: A few seconds after the jumper is installed, the LVD will automatically reset. If this happens before you test the manual reset, remove the jumper, wait for the light to come on, reinstall the jumper and try the switch again.

9) For 12 volt and 24 volt controllers only; Measure the voltage between Battery(+) and   Battery(-). It should be approximately equal to the float voltage. (Refer to the SPECIFICATIONS for actual values.)

10) If the controller fails any of these tests, it is defective. If all tests are passed, the problem is most likely elsewhere in the system.