Battery cell bypass circuit

A high reliability battery system having a first battery system terminal and a second battery system terminal, the battery system comprising:

• a plurality of battery cells, each having a positive terminal and a negative terminal, wherein said battery cells are connected in series between said first battery system terminal and said second battery system terminal;
• a plurality of bypass circuits, wherein each of said bypass circuits has a first terminal connected to the positive terminal of a corresponding battery cell, and a second terminal connected to the negative terminal of said corresponding battery cell, wherein each of said bypass circuits comprises:
• a first plurality of diodes connected in series between said positive terminal and said negative terminal, wherein each of said first plurality of diodes are connected with their forward direction from said positive terminal to said negative terminal;
• a second plurality of diodes connected in parallel with each other between said negative terminal and an intermediate terminal, wherein each of said diodes of said second plurality has its cathode connected to said negative terminal and its anode to said intermediate terminal;
• and
• a third plurality of diodes connected in parallel with each other between said intermediate terminal and said positive terminal, wherein each of said diodes of said third plurality has its cathode connected to said intermediate terminal and its anode connected to said positive terminal.

An electrical bypass circuit for connection in parallel with a battery cell having a positive terminal and a negative terminal, wherein the bypass circuit is packaged in a single hybrid package, said bypass circuit comprising:

• a first metal terminal for connection to said positive terminal of said battery cell;
• a second metal terminal, electrically isolated from said first metal terminal, for connection to said negative terminal of said battery cell;
• a first plurality of diodes mounted on an electrically insulating base so that said diodes are connected in electrical series, and the cathode of the first diode in said series is connected through said insulating base to said first metal terminal, and the anode of the last diode in said series is connected through said insulating base to said second metal terminal, wherein said diodes are connected with their forward direction from said first terminal to said second terminal;
• a common metal terminal mounted on said electrically insulating base;
• a second plurality of diodes, each mounted on said common metal terminal so that its anode is connected to said common metal terminal;
• a third plurality of diodes, each mounted on said common metal terminal so that its cathode is connected to said common metal terminal;
• a first metal connector coupling the anodes of said third plurality of diodes and said first metal terminal;
• and
• a second metal connector coupling the cathodes of said second plurality of diodes and said second metal terminal.