Self-Contained Electrical Power Supply

a source of electrical energy required for the operation of devices and systems not connected to electric power lines. There are self-contained electrical power supplies structurally connected to the user device (for example, galvanic or storage batteries in flashlights and miniature radio receivers, solar batteries on artificial earth satellites, starter and drive storage batteries on vehicles, and others) and portable self-contained electrical power supplies not directly connected to the user device (for example, transportable electric power plants, electric generators on trains, and others).