This paper examines the emerging technology of batteries incorporating carbon in the negative plate to affect a parallel capacitance within the battery itself. Using a frequency domain approach in conjunction with low frequency static tests and step responses an UltraBattery™ is examined. Initial examinations using the Randles' model lead to development of a modified model to better represent the battery parameters. These findings then expand the work to examine a similar conventional battery connected in a parallel network with a supercapacitor bank, allowing comparisons to be made and performance criteria to be established.