Some embodiments include apparatus and methods for using a first node to couple to a battery, a second node to couple to a terminal of an interface, and a precharge circuit unit coupled to the first and second nodes. The precharge circuit can operates to cause a first current to flow from the first node to the second node through a transistor of the precharge circuit unit based on first values of voltages at the first and second nodes, and to cause a second current to flow from the second node to the first node through the transistor based on second values of voltages at the first and second nodes.