Method for determining an effective voltage of a battery

A method for determining an effective battery voltage of a battery, comprising:

• measuring a battery voltage over time;
• determining a first amount of time that the measured battery voltage falls within a first predetermined voltage range, and a second amount of time that the measured battery voltage falls within a second predefined voltage range;
• calculating a first ratio of the difference between the first amount of time and the second amount of time;
• repeating the determining and calculating steps to calculate other ratios;
• and
• determining a first peak point of the calculated first and other ratios.

A system for determining an effective voltage of a battery, the system comprising:

• a motor control unit to output motor torque control commands;
• a battery management system to manage the charging state of the battery, the battery management system comprising:
• logic for detecting a battery voltage at a predetermined interval;
• logic for counting a number of times the battery voltage is detected within a series of predetermined voltage ranges;
• logic for calculating a ratio of a change of the counted number with respect to a change of the battery voltage;
• and
• logic for determining a first peak point of the calculated ratio;
• and
• a hybrid control unit to control at least one of the motor control unit and the battery management system through control commands.