A battery pack is a set of any number of (preferably) identical batteries or individual battery cells. They may be configured in a series, parallel or a mixture of both to deliver the desired voltage and current. The term battery pack is often used in reference to cordless tools, radio-controlled hobby toys, and battery electric vehicles. Components of battery packs include. SOC, or state of charge, is the equivalent of a fuel quantity remaining. SOC cannot be determined by a simple voltage measurement, because the terminal voltage of a battery may stay substantially constant until it i. An advantage of a battery pack is the ease with which it can be into or out of a device. This allows multiple packs to deliver extended runtimes, freeing up the device for continued use while charging the removed pack se.