Patent attributes
A characteristic, such as State Of Health (SOH) or State Of Charge (SOC), is estimated for an Energy Storage System (ESS) by supplying a pre-determined signal to the ESS, measuring a response signal output by the ESS, and obtaining an impedance spectrum of the ESS. In one example, the ESS is one of several electrochemical battery packs of an electric vehicle. The pre-determined signal is a current signal generated by a switching power converter that transfers charge from the battery pack to other battery packs or transfers charge from the other battery packs onto the battery pack. The pre-determined signal is generated without disrupting any load supplied by the battery packs. The battery pack outputs a voltage signal in response to receiving the pre-determined current signal. A processor obtains an impedance spectrum using the current and voltage signals, and thereby obtains an SOH and SOC estimate of the battery.