Under "normal" circumstances were all guns in the battery supplied with power from the common power grid. Besides that, a power plant was build in the center of the battery area, to provide the necessary power in case of the common power disappears.

Entrance to the power plant in the battery area.

If this power plant, for numerous reasons, wasn't able to provide the battery with the necessary power either, every gun had its own internal power supply, that not only could supply itself with power, but it could also supply the other guns in the battery if necessary.

Internal Power Station placed inside the emplacement of the gun. Pictures is from MAA 118's sister battery in Kristiansand (VARA), but was equipped with the same machinery.