Patent ID: 7750641

Claim:
A method for monitoring a battery, the battery having a first plurality of cells electrically coupled in series to one another, the first plurality of cells comprising a second plurality of cells and a third plurality of cells electrically coupled together at a node, each cell of the first plurality of cells having a desired output voltage level during desired operation and failing in a shorted operational condition, the method comprising: measuring a first voltage level of the first plurality of cells of the battery when the first plurality of cells are not electrically coupled to a load; measuring a second voltage level at the node between the second plurality of cells and the third plurality of cells when the first plurality of cells are electrically coupled to the load; calculating a first number of failed cells in the first plurality cells based on the first voltage level, the desired output voltage level of each cell of the first plurality of cells and a number of cells in the first plurality of cells; calculating a second number of failed cells in the second plurality cells based on the first number of failed cells, the desired output voltage level of each cell of the first plurality of cells, and the second voltage level; and calculating a third number of failed cells in the third plurality cells based on the first number of failed cells, the desired output voltage level of each cell of the first plurality of cells, and the second voltage level.