Method and apparatus for controlling electric power flow in a battery system

A method for controlling electric power flow in a battery system for a vehicle, wherein the battery system includes a plurality of lithium-ion battery packs that are electrically connected via a wiring harness, and wherein the battery system is electrically connected via the wiring harness to a power bus, the method comprising:

• monitoring, via a plurality of sensors, parameters associated with the plurality of battery packs;
• determining states of charge and impedances for the plurality of lithium-ion battery packs;
• determining an internal circulating current being transferred via the wiring harness;
• and
• controlling electric power transfer through the wiring harness and the power bus by introducing a resistive load onto the power bus such that the internal circulating current is less than an internal circulating current limit.

An electric power system for a vehicle, comprising:

• a battery system including plurality of battery packs, a plurality of sensors arranged to monitor the battery packs, a high-voltage DC power bus, a plurality of switches interposed between the plurality of battery packs and the power bus, an electric machine, a wiring harness, and a controller;
• wherein the plurality of battery packs are electrically connected via the wiring harness;
• wherein the plurality of battery packs are electrically connected via the wiring harness to the power bus;
• wherein the controller is in communication with the plurality of sensors, the plurality of switches, and the electric machine;
• wherein the controller includes an instruction set, wherein the instruction set is executable to:
• monitor, via the plurality of sensors, parameters associated with the plurality of battery packs,
• determine states of charge and impedances for the plurality of battery packs,
• determine an internal circulating current that is being transferred between the plurality of battery packs via the wiring harness based upon the states of charge and the impedances of the battery packs, and
• control electric power transfer through the wiring harness and the power bus by introducing a resistive load onto the power bus such that the internal circulating current is less than an internal circulating current limit.