Validation of single frequency Z measurement for standby battery state of health determination

Impedance has been discussed for a long time as an indicator for the state of health (SOH) of lead-acid batteries for standby applications such as UPS systems. The research contains the analysis of the relation between capacity and impedance measurement at different frequencies. Several batteries of different manufacturers and capacity were aged systematically and the impedance measurements were done under similar conditions as in real UPS systems. Impedance measurements with the low cost device and full scale laboratory equipment and capacity tests have been performed periodically.