An improved self-contained electronic device for testing storage batteries and other dc sources is disclosed. The testing device is electrically connected to the battery by means of temporary spring clips. Adjustments are set to the particular electrical rating and temperature of the battery. The device then employs small-signal dynamic measurements to determine whether or not the battery is capable of delivering a specified amount of power dictated by the battery's rating and temperature. The invention thus provides simple 'pass-fail' information just as does a conventional load test apparatus but without the disadvantages of the latter.