Battery impedance: Farads, milliohms, microhenrys

THE ELECTRICAL RESISTANCE of storage batteries is important to two groups of people. Designers of telephone equipment need to know the resistance to alternating current in order to evaluate the cross talk between simultaneous telephone conversations which must pass through the central station battery. They must also be able to evaluate the amount of filtering required to remove hum, noise, and switching pulses from the output of the charging and switching equipment. In addition, designers of central power stations need to know the resistance of the battery which must supply short pulses of power to operate electric switches.