Patent ID: 8063607

Claim:
An energy storage system comprising: a plurality of battery cells configured to be electrically connected to a power source, said plurality of battery cells comprising: a first battery cell; and a second battery cell; and a controller in communication with said first and second battery cells, said controller controls an electrical current supplied to said first and second battery cells, such that a first charging method is utilized when a voltage potential of said first and second battery cells is less than a first voltage potential threshold, respectively, and a second charging method is utilized when said voltage potential of said first and second battery cells is equal to or greater than said first voltage potential threshold, wherein said first charging method charges at least one of said first and second battery cells at a greater rate than said second charging method, and said first charging method is utilized to charge said first battery cell prior to being utilized to charge said second battery cell when said voltage potential of said first battery cell is below said first voltage potential threshold and greater than said voltage potential of said second battery cell, and wherein the second charging method charges one of the first and second battery cells having the lowest voltage potential equal to or greater than the first voltage potential threshold prior to charging the other of the first and second battery cells.