	US 7,550,946 B2
	Method and apparatus for real-time life estimation of an electric energy storage device in a hybrid electric vehicle
Andrew M. Zettel, Ann Arbor, Mich. (US); and Anthony H. Heap, Ann Arbor, Mich. (US)
Assigned to GM Global Technology Operations, Inc., Detroit, Mich. (US)
Filed on Jun. 07, 2006, as Appl. No. 11/422,691.
Prior Publication US 2007/0285061 A1, Dec. 13, 2007
Int. Cl. H02J 7/00 (2006.01)

U.S. Cl. 320—132 [320/150; 324/430]

12 Claims

9. Apparatus for determining state-of-life of an electrical energy storage device operative to exchange electrical energy with a hybrid vehicular powertrain including first and second electric machines each machine operable to impart torque to a two-mode, compound-split electromechanical transmission having four fixed gear ratios and two continuously variable operating modes, comprising:

a temperature sensor adapted for sensing temperature of the electrical energy storage device; and

a computer based controller adapted to receive a signal indicative of sensed electrical energy storage device temperature; said computer based controller including a storage medium having a computer program encoded therein, said computer program comprising:

code for monitoring electrical current through the electrical energy storage device;

code for monitoring a state-of-charge of the electrical energy storage device;

code for monitoring temperature of the electrical energy storage device during periods of vehicle activity;

code for monitoring temperature of the electrical energy storage device during periods of vehicle inactivity;

code for monitoring a state-of-life of the electrical energy storage device based upon the electrical current, the state-of-charge, and the temperature of the electrical energy storage device during periods of vehicle activity and during periods of vehicle inactivity; and

code to determine state-of-life of the electrical energy storage device, based upon the electrical current, the state-of-charge of the electrical energy storage device, and the temperature of the electrical energy storage device during periods of vehicle activity and during periods of vehicle inactivity, the code to determine the state-of-life including code for fixing state-of-life to a predetermined value when said internal resistance indicates an incipient end of life of the electrical energy storage device;

code for detecting an internal resistance change over time that is greater than a minimum amount; and code for fixing the state-of-life to the predetermined value when the internal resistance is greater than the minimum amount.