Primary Battery

—1. A group of primary cells connected together in order to act as a single electric source. 2. In gas engine ignition, a primary battery generally consists of between four and six open-circuit dry cells in series, giving a pre ure of between 1 and 14 volts per cell. Two such batteries are generally included in the outfit, either of them being switched into circuit, as required, or both being connected in multiple, to give a greater current at the same voltage In many cases the chemical battery is used only for sparking at the start of the engine, and until the magneto or dynamo has attained sufficient speed for continuous effect, being then automatically switched out of circuit. It is nece ary to use the open circuit type of cell, since the current must be periodically interrupted.