Patent ID: 7646166

Claim:
An energy management controller for a vehicle comprising: a processor configured to: estimate an initial diffusion voltage, calculate a diffusion voltage using an equation based on a diffusion circuit model and the estimated initial diffusion voltage, and determine a battery condition parameter using the diffusion voltage, wherein to estimate the initial diffusion voltage, the processor is further configured to: determine a first voltage as a difference between a key-off voltage measured when the vehicle is turned off and a key-on voltage measured when the vehicle is turned on, select a starting diffusion voltage based on a predetermined curve of diffusion voltage versus time, determine a determined diffusion voltage based on the first diffusion voltage and an elapsed time between when the vehicle is turned off and when the vehicle is turned on, and estimate the initial diffusion voltage as the determined diffusion voltage if the difference between the starting diffusion voltage and the determined diffusion voltage matches, within a predetermined amount, the first voltage; and a memory coupled to the processor, the memory configured to store the battery condition parameter.