Battery packs achieve the desired operating voltage by connecting several cells in series, with each cell adding to the total terminal voltage. Parallel connection attains higher capacity for increased current handling, as each cell adds to the total current handling. Some packs may have a combination of serial and parallel connections.
Early batteries were in jars, but mass production changed the packaging to the cylindrical design. The year 1896 pioneered the large F cell for lanterns; the D cell followed in 1898, the C cell in 1900, and the popular AA was introduced in 1907. Design criteria and cost considerations required new battery formats that offer distinct advantages over the cylindrical design.
Experimental batteries live mostly in sheltered laboratories, communicating to the outside world through rosy reports generated for investors. Some systems show good potential, but many are years away from becoming commercially viable. Others disappear from the scene and die gracefully in the lab without hearing of their passing. Below are the most promising experimental batteries worth mentioning in alphabetical order.
The media tells us of wonderful new batteries being developed that promise long runtimes and are paper-thin, durable, cheap and environmental friendly. While these experimental packs may be able to produce a voltage, the downsides are seldom revealed. The typical shortcomings are weak load capabilities and short cycle life. Yes, even a lemon can be made into a battery. Just poke a copper coin and galvanized nail into the innards. The power is low and you need 500 lemons to light a flashlight bulb.