Abstract: Apparatus and method are provided for measuring the series resistance of each individual cell of a battery bank for establishing the readiness of the batteries. The invention comprises a switch in series with a load, connected across each cell of the battery. An electronic switch momentarily imposes the load on the cell and the value of the current drawn from the battery and the voltage across it is measured with an A/D device. A controller directs a plurality of the switched loads on a plurality of cells. The A/D device and controller on each cell communicates their measurements to a remote host computer, preferably via an RF serial modem. The host computer calculates the internal resistance and provides alarm and other reporting functions. Further, as the measurement imposes a small energy drain on the cell, through independent adjustment of the frequency of measurement for each cell, over-charging of the individually cells can be equalized.