A computerized ac loss measurement system was developed and more than 50 magnets were measured. The ac losses were very much dependent on various factors such as conductor surface and pressure applied to coil windings. Statistical correlation between quench current and ac loss will be shown. From the measurements of magnets made of different kinds of cables, most of the eddy current loss was found to be in the inner coil of the double layer structure. Among the three kinds of eddy current loops, the one which comes from the interconnection between crossing strands was proved to be the major part of the eddy current loss. Such an eddy current can be almost eliminated, by the use of a copper oxide resistive layer between strands. Thus, the Energy Doubler/Saver magnets, will be operated up to 4.5T with a loss of about 450J/cycle per each dipole magnet. To estimate real time power loss instead of total loss throughout whole cycle, a new method was tried and successful results were obtained.