Cars with wheels driven by battery-powered electric motors, continuously or intermittently, have become a hot topic. These “green” vehicles rely on batteries of series-connected cells to obtain sufficiently high voltage to operate the motor efficiently. Such high-voltage (HV) stacks are used in all-electric vehicles (EV)—as well as hybrid electric vehicles (HEV), which rely on an internalcombustion engine (ICE) for charging and (in many cases) shared propulsion. EVs must be plugged into a power source for charging; some newer hybrids are designed as plug-in hybrid electric vehicles (PHEV), which are considered to be essentially EVs with an ICE for range extension.