This set looks, from the outside, no different from any other portable radio of the day. Only when one opens the back do we discover that this was designed to use a single 2 volt lead/acid accumulator, rather than the newer types of combined 'dry' cell battery. In this regard, it sets a precedent for the later models in the GE lineup that use the same system.
Internally, the Willard accumulator sits in its own small compartment. This powers a removable vibrator for the 90V 'B' supply and heats the filaments directly. Although this set can be 'run' from the mains, it must be done so with a healthy battery in place as, in fact, the AC mains power merely supplies a battery charging circuit. No battery = no go.
This presents a problem for using sets of this type. Although it is possible to substitute the wet battery with a modern supply that can still be used in its stead (Tony Maher, in Australia, designed such a system to use conventional D cells), it is not possible to use these newer replacements and run the radio on mains power due to the difference in internal resistance between the wet-cell and its substitute.