A battery monitoring system, comprising: a current sensor electrically coupled in series with a battery cell; a voltage sensor electrically coupled in parallel to the battery cell; a microcontroller configured to obtain cell current values (I1, 12) of a cell current flowing through the battery cell from the current sensor at a first update frequency of M times per second; the microcontroller being configured to obtain cell voltage values (V1, V2) of the battery cell from the voltage sensor, in parallel to the obtaining of the cell current values, with respect to electrical ground, at a second update frequency of N times per second, wherein M is equal to or greater than N; the microcontroller being configured to determine a rate of change of cell current utilizing two cell current values of the cell current values, at a third update frequency of R times per second, where R is less than M and R is less than N; the microcontroller being configured to determine a rate of change of cell voltage utilizing two cell voltage values of the cell voltage values, at the third update frequency, wherein a time between an acquisition of a first one of the two cell voltage values and an acquisition of a first one of the two cell current values is a value near zero, and a time between an acquisition of a second one of the two cell voltage values and an acquisition of a second one of the two cell current values is a value near zero; the microcontroller being configured to determine a filtered ohmic resistance value based on the rate of change of cell voltage, the rate of change of cell current, and a prior filtered ohmic resistance value, if a numerical sign of the rate of change of cell voltage is identical to a numerical sign of the rate of change of cell current, and the rate of change of cell voltage is less than or equal to an upper threshold of allowable rates of cell voltage change, and the rate of change of cell voltage is greater than or equal to a lower threshold of allowable rates of cell voltage change; the microcontroller being configured to determine the filtered ohmic resistance value to be a prior filtered ohmic resistance value, if the numerical sign of the rate of change of cell voltage is not identical to the numerical sign of the rate of change of cell current, or the rate of change of cell voltage is not less than or equal to the upper threshold of allowable rates of cell voltage change, or the rate of change of cell voltage is not greater than or equal to the lower threshold of allowable rates of cell voltage change. a current sensor electrically coupled in series with a battery cell; a voltage sensor electrically coupled in parallel to the battery cell; a microcontroller configured to obtain cell current values (I1, 12) of a cell current flowing through the battery cell from the current sensor at a first update frequency of M times per second; the microcontroller being configured to obtain cell voltage values (V1, V2) of the battery cell from the voltage sensor, in parallel to the obtaining of the cell current values, with respect to electrical ground, at a second update frequency of N times per second, wherein M is equal to or greater than N; the microcontroller being configured to determine a rate of change of cell current utilizing two cell current values of the cell current values, at a third update frequency of R times per second, where R is less than M and R is less than N; the microcontroller being configured to determine a rate of change of cell voltage utilizing two cell voltage values of the cell voltage values, at the third update frequency, wherein a time between an acquisition of a first one of the two cell voltage values and an acquisition of a first one of the two cell current values is a value near zero, and a time between an acquisition of a second one of the two cell voltage values and an acquisition of a second one of the two cell current values is a value near zero; the microcontroller being configured to determine a filtered ohmic resistance value based on the rate of change of cell voltage, the rate of change of cell current, and a prior filtered ohmic resistance value, if a numerical sign of the rate of change of cell voltage is identical to a numerical sign of the rate of change of cell current, and the rate of change of cell voltage is less than or equal to an upper threshold of allowable rates of cell voltage change, and the rate of change of cell voltage is greater than or equal to a lower threshold of allowable rates of cell voltage change; the microcontroller being configured to determine the filtered ohmic resistance value to be a prior filtered ohmic resistance value, if the numerical sign of the rate of change of cell voltage is not identical to the numerical sign of the rate of change of cell current, or the rate of change of cell voltage is not less than or equal to the upper threshold of allowable rates of cell voltage change, or the rate of change of cell voltage is not greater than or equal to the lower threshold of allowable rates of cell voltage change.