The paper describes the design of the device that is used to improve performance of internal com-bustion engine starting system, especially, in cold weather, extend lifetime of starting battery and eliminate voltage drop during starting process. As additional energy storage supercapacitors are uti-lized due to high power density, low series re-sistance and superior cycle performance. The ad-dition storage is connected through controllable switch to increase stored energy and connect ad-ditional storage only when it is required. A proto-type is tested under real conditions; experimental results are registered and included in the paper. The results shows that such device significantly re-duces current from the battery and provides successful cold cranking of the engine.