Methods for reconfigurable battery charger control

1. A method of charging a vehicle battery pack having a plurality of parallel strings, each of the parallel strings comprising one or more battery cells, comprising:

(a) determining a voltage imbalance between at least two of the parallel strings exceeds a threshold magnitude, and determining that a first group of one or more of the battery cells of a first one of the parallel strings has a lower voltage potential than a second group of one or more of the cells of a second one of the parallel strings;

(b) in response to the determination in step (a), electrically reducing the voltage imbalance between the at least two parallel strings using a series circuit including the first group of the cells, wherein electrically reducing the voltage imbalance includes:

(b1) determining whether the vehicle is connected to an external source of electrical power;

(b2) determining whether the vehicle is in use; and

(b3) in response to the determinations in steps (b1) and (b2):

when the vehicle is determined to be connected to an external source of electrical power, electrically reducing the voltage imbalance by connecting the first group of the cells in series with the external power supply, such that the voltage imbalance is electrically reduced by increasing the voltage potential of the first group of the cells;

when the vehicle is determined to be in use, electrically reducing the voltage imbalance by connecting the second group of the cells in series with an electrical load of the vehicle, such that the voltage imbalance is electrically reduced by reducing the voltage potential of the second group of the cells; and

when the vehicle is determined to not be connected to an external source of electrical power and also determined to not be in use, alternating a connection of an electrical load in series with the first group of cells and the second group of cells using pulse width modulation, such that the voltage imbalance is electrically reduced by increasing the voltage potential of the first group of the cells and by reducing the voltage potential of the second group of the cells; and

(c) reconnecting the parallel strings in an electrical circuit in parallel to each other, the parallel strings thereby configured to supply power to the vehicle.

2. The method of claim 1 , further comprising disconnecting the first group of cells from the second group of cells.

3. The method of claim 1 , further comprising supplying power to the vehicle after reconnecting the parallel strings in the electrical circuit in parallel to each other.

4. The method of claim 1 , further comprising connecting the battery cells of the at least two parallel strings in a series circuit, and charging the battery cells while they are connected in the series circuit.

5. A method of charging a vehicle battery pack having a plurality of parallel strings, each of the parallel strings comprising one or more battery cells, comprising:

(a) connecting the battery cells of at least two of the parallel strings in a series circuit;

(b) charging the battery cells while they are connected in the series circuit;

(c) determining a voltage imbalance between at least two of the parallel strings exceeds a threshold magnitude after charging the battery cells, and determining that a first group of one or more of the battery cells of a first one of the parallel strings has a lower voltage potential than a second group of one or more of the cells of a second one of the parallel strings;

(d) in response to the determination in step (c), electrically reducing the voltage imbalance between the at least two parallel strings using a series circuit including the first group of the cells, wherein electrically reducing the voltage imbalance includes:

(d1) determining whether the vehicle is connected to an external source of electrical power;

(d2) determining whether the vehicle is in use; and

(d3) in response to the determinations in steps (d1) and (d2):

when the vehicle is determined to be connected to an external source of electrical power, electrically reducing the voltage imbalance by connecting the first group of the cells in series with the external power supply, such that the voltage imbalance is electrically reduced by increasing the voltage potential of the first group of the cells;

when the vehicle is determined to be in use, electrically reducing the voltage imbalance by connecting the second group of the cells in series with an electrical load of the vehicle, such that the voltage imbalance is electrically reduced by reducing the voltage potential of the second group of the cells; and

when the vehicle is determined to not be connected to an external source of electrical power and also determined to not be in use, alternating a connection of an electrical load in series with the first group of cells and the second group of cells using pulse width modulation, such that the voltage imbalance is electrically reduced by increasing the voltage potential of the first group of the cells and by reducing the voltage potential of the second group of the cells; and

(e) reconnecting the parallel strings in an electrical circuit in parallel to each other, the parallel strings thereby configured to supply power to the vehicle.

6. The method of claim 5 , further comprising disconnecting the first group of cells from the second group of cells.

7. The method of claim 5 , further comprising supplying power to the vehicle after reconnecting the parallel strings in the electrical circuit in parallel to each other.

8. A method of reconfiguring a vehicle battery pack having a plurality of parallel strings, each of the parallel strings comprising one or more battery cells, comprising:

(a) connecting the battery cells of at least two of the parallel strings in a series circuit for charging the vehicle battery pack;

(b) determining a voltage imbalance between at least two of the parallel strings exceeds a threshold magnitude, and determining that a first group of one or more of the battery cells of a first one of the parallel strings has a lower voltage potential than a second group of one or more of the cells of a second one of the parallel strings;

(c) in response to the determination in step (b), electrically reducing the voltage imbalance between the at least two parallel strings using a series circuit including the first group of the cells, wherein electrically reducing the voltage imbalance includes:

(c1) determining whether the vehicle is connected to an external source of electrical power;

(c2) determining whether the vehicle is in use; and

(c3) in response to the determinations in steps (c1) and (c2):

when the vehicle is determined to be connected to an external source of electrical power, electrically reducing the voltage imbalance by connecting the first group of the cells in series with the external power supply, such that the voltage imbalance is electrically reduced by increasing the voltage potential of the first group of the cells;

when the vehicle is determined to be in use, electrically reducing the voltage imbalance by connecting the second group of the cells in series with an electrical load of the vehicle, such that the voltage imbalance is electrically reduced by reducing the voltage potential of the second group of the cells; and

when the vehicle is determined to not be connected to an external source of electrical power and also determined to not be in use, alternating a connection of an electrical load in series with the first group of cells and the second group of cells using pulse width modulation, such that the voltage imbalance is electrically reduced by increasing the voltage potential of the first group of the cells and by reducing the voltage potential of the second group of the cells; and

(d) reconnecting the parallel strings in an electrical circuit in parallel to each other, the parallel strings thereby configured to supply power to the vehicle.

9. The method of claim 8 , further comprising disconnecting the first group of cells from the second group of cells.

10. The method of claim 8 , further comprising supplying power to the vehicle after reconnecting the parallel strings in the electrical circuit in parallel to each other.