Abstract: A system and method is provided for selecting a test load and/or bias resistor utilized in an expandable load system employing a backup power source. The test load and/or bias resistor is selected based on the actual load present in the expandable system. The backup power source is periodically tested during normal operation of the expandable load system utilizing the test load. A test load is provided that is sized for the actual load of a local load under worse case conditions. If an expansion load is connected to the local load the test load is adjusted, so that the test load is based on the actual load of the local load and the expansion load. Additionally, a bias resistance can be provided for driving a switch that allows power to be provided to the local load during power loss mode. If an expansion load is connected to the local load, the bias resistance is adjusted to correspond to a bias resistance necessary to provide the current for the actual load of the local load and the expansion load.