A relatively young technology based on capacitive deionization (CDI) is known to be environmentally friendly, energy efficient and economical. In our previous work, we were able to recover almost 70% of energy by solely controlling the circuit connections of the CDI systems. However, details on the energy loss due to external resistance and other contributing factors including the power supply and the circuit connections to current collectors were not explored. The electric background wherein the uni-polar circuit connection seemed to exhibit higher charging resistance compare to bi-polar circuit, was also unknown. Thus, the electrical behavior of a CDI single-unit cell, uni- and bi-polar circuit stack systems, and energy recovering system were evaluated to understand the electric behavior during charge/discharge process.