State based full and empty control for rechargeable batteries

摘要

State based full and empty control for rechargeable batteries that will assure a uniform battery empty condition, even in the presence of a load on the battery. A fuel gauge provides a prediction of the open circuit voltage of the battery, and when the predicted open circuit voltage of the battery reaches the predetermined open circuit voltage of an empty battery, the load is terminated, after which the battery will relax back to the predetermined open circuit voltage of an empty battery. A similar technique is disclosed for battery charging, allowing faster battery charging without overcharging. Preferably an RC battery model is used as the fuel gauge to provide the prediction, but as an alternative, a coulomb counter may be used to provide the prediction, with error correction between successive charge discharge cycles.

主权项

1. A method of determining an empty state of a rechargeable battery comprising:
modeling the battery to predict an open circuit voltage of the battery, even in the presence of a variable load on the battery; predetermining an open circuit voltage at which the battery is to be considered fully discharged that is independent of the variable load on the battery; in the presence of varying loads on the battery, allowing the battery to discharge to a terminal voltage below the open circuit voltage at which the battery will be considered discharged until the open circuit voltage prediction reaches the open circuit voltage at which the battery is to be considered fully discharged.