Systems and methods for overcharge protection and charge balance in combined energy source systems

An energy source system for a vehicle, comprising:

• a battery having a plurality of cells coupled in series with one another;
• and
• a plurality of ultracapacitors coupled in series with one another, wherein a combined voltage of the battery cells and a combined voltage of the one or more ultracapacitors is within a range of between approximately 36V and approximately 60V.

An energy source system for a vehicle, comprising:

• a battery comprising a plurality of cells coupled in series with one another and configured to be coupled to an alternator of the vehicle;
• and
• one or more ultracapacitors coupled in series with one another and configured to be coupled to starting components of the vehicle, wherein the battery and the one or more ultracapacitors are coupled to one another in a parallel arrangement, and wherein a combined voltage of the battery cells and a combined voltage of the one or more ultracapacitors is approximately 48V.