A battery health monitor (BHM) that operates as a battery-mountable full-spectrum alternating current (ac) impedance meter that facilitates monitoring a state-of-charge and a state-of-health of a battery. The BHM is used for monitoring one or more electrical parameters, e.g., impedance, of a battery....http://www.google.de/patents/US7554294?utm_source=gb-gplus-sharePatent US7554294 - Battery health monitor
