In AC power systems, how is DC typically obtained for charging batteries?

In AC power systems, direct current (DC) is typically obtained for charging batteries through the use of rectifiers. Rectifiers are electronic devices or circuits that convert alternating current (AC) into direct current (DC). They achieve this by allowing current to flow in only one direction, effectively blocking one half of the AC waveform, which results in a pulsating DC output.

This conversion is essential in applications where batteries need to be charged from an AC mains supply, as batteries operate on DC. The rectified output can then be smoothed using additional components like capacitors or inductors to provide a more stable DC voltage suitable for charging batteries.

In contrast, inverters are used to convert DC back to AC, and transformers serve to step up or step down voltage levels of AC power but do not directly convert AC to DC. The option of using batteries as a source of DC does not answer the question regarding how DC is obtained from an AC system. Therefore, the use of rectifiers is the correct method for obtaining DC in this context.