Electrical power as a hidden naval advantage before World War II

Which power and engineering advances, other than nuclear weapons, could have changed World War II most?

Mature electrical generation and powered systems could have enabled better radar and weapon installations earlier.

Dependable higher-current electrical systems would have enabled several less visible improvements. More electrical power could support rotating radar sets and the motors and electro-hydraulics needed for rapid, powered gun mountings. A mature installation might have made British 4.5-inch dual-purpose weapons practical earlier and allowed destroyers such as the Tribals to use them effectively. Combined with radar, Barracuda torpedo-dive bombers, and purpose-designed carrier fighters, that change sketches a much stronger early-war fleet. Most of the component ideas already existed in the late 1930s, but cost, integration, and the pressure of wartime production prevented them from maturing together. System integration and development time can matter as much as the invention date of any single technology.