Command Module Batteries

The CM carries a total of five batteries. Two silver oxide-zinc batteries are mounted in the Lower Equipment Bay and are used only for energising the pyrotechnic devices for CM/SM separation, parachute deployment and separation, S-IVB separation, launch escape tower separation among other functions. They are not recharged. Three more silver oxide-zinc batteries supplement the power from the fuel cells during busy periods such as engine burns and can be recharged from the fuel cells when demand is low. They also provide power for the CM after the SM has been jettisoned, through entry, landing and post-landing operations. The controls for the electrical system are on the right of the Main Display Console, where Jim is seated. To charge battery B, he must ensure it is not online to the spacecraft's power distribution buses before switching it to the output from the battery charger. The voltage of the battery can be monitored while it is charging by switching the DC indicator to the charger. (ap15fj)