A system and method for controlling ambient temperature at a power-consuming site includes a hybrid generator-battery power system. The generator-battery power system includes an engine-generator set and one or more DC-powered batteries that alternately share the site load. Thus, the method includes providing one or more temperature sensors communicatively coupled to a battery management system at the power-consuming site. Another step includes monitoring the ambient temperature of the power-consuming site via the one or more temperature sensors when one or more of the DC-powered batteries are discharging (i.e. when the engine-generator set is off). The method also includes sending, via the battery management system, a start-up command to the engine-generator set when the ambient temperature of the power-consuming site reaches a threshold temperature such that the engine-generator set can provide AC power to an air conditioning unit at the power-consuming site.