Patent ID: 9164151
Filing Date: 2015-10-20
Classification: G01R

Abstract:
1. A system for determining isolation resistances of a battery pack, the battery pack having a housing and at least first and second battery modules disposed in the housing, the battery pack further having first and second electrical terminals, comprising: a voltage source configured to be electrically coupled to the first and second electrical terminals of the battery pack, the voltage source further configured to apply a first output voltage level at a first time between the first and second electrical terminals when the first and second battery modules are not electrically coupled in series with one another; a voltage meter configured to measure a first voltage level between the first electrical terminal and the housing when the first output voltage level is being output; the voltage meter further configured to measure a second voltage level between the first electrical terminal and the housing, when the first output voltage level is being output, and a resistor is electrically coupled between the first electrical terminal and the housing; the resistor having a predetermined resistance level; the voltage meter further configured to measure a third voltage level between the second electrical terminal and the housing when the first output voltage level is being output; the voltage meter is further configured to measure a fourth voltage level between the second electrical terminal and the housing, when the first output voltage level is being output, and the resistor is electrically coupled between the second electrical terminal and the housing; a microprocessor programmed to operably communicate with the voltage meter, the microprocessor further programmed to determine a first isolation resistance value associated with the battery pack at the first time based on the first voltage level, the second voltage level, the third voltage level, and the predetermined resistance level; the microprocessor further programmed to determine a second isolation resistance value associated with the battery pack at the first time based on the first voltage level, the third voltage level, the fourth voltage level, and the predetermined resistance level; and the microprocessor further programmed to determine which of the first isolation resistance value and the second isolation resistance value has a smallest value relative to one another, and to store the smallest value of the first and second isolation resistance values in a memory device.