[This note covers all of the notebooks in Group 3: Battery Endurance Book and Work Books.]

The ten extant notebooks in this group (Battery Endurance Book No. 1 and Work Books, Nos. 1-10; Work Book 4 has not been located) cover the period November 1904- December 1906. They consist of an Endurance Book and nine Work Books, which describe the performance and characteristics of experimental storage batteries. The first book, entitled "Endurance Book #1," was used by Edison and later by Walter E. Holland to rate the endurance of groups of cells. Included are tabulated ratings of the performance of some of the cells numbered from 4060 through 9343. Separately tabulated measurements give caliper readings before and after the tests, which possibly refer to the swelling of pockets in the electrodes of the "E" type batteries. The inside front cover contains an "Index to Section I and II," listing the order of entries in the book. Two indexes in the middle of the book provide a partial description of the experimental characteristics of each group of cells.

Although the individual entries in the Work Books are less detailed than those in the Endurance Book, the books in this set contain records of endurance tests for all cells numbered from 4000 through 13127. Most of the entries in Books 1-5 are by Edison. The succeeding books show a steady decline in entries by Edison, and the last book contains only entries by Walter E. Holland and by other unidentified experimenters. At the beginning of the first Work Book is the following notation by Edison: "New experiments started at Laboratory in our new test room to discover why nickel elements in some cases lose their amp capacity after being in use and also to discover a remedy that is practical and commercial."