Electronic devices requiring portable power sources typically have compartments for housing batteries, battery packs, or battery holders, the battery packs or battery holders having batteries therein. Battery holders have been employed for holding various forms of batteries, such as back up batteries for real time clocks in desk top computers. The placement and keeping of dry batteries are often connected with the electrical appliances or products used. A battery holder receives and retains a dry battery, it comprises a cylindrical body having a first flat end surface, serving as a negative terminal, and a second end surface from which a cylinder concentrically projects, serving as a positive terminal. There are some dry batteries which are stored separately from the electrical appliances used. In addition, there are also battery chargers for keeping rechargeable nickel-cadium batteries, which may be recharged when the battery chargers are connected to an AC electric power source which is rectified to lower its voltage.
