He did not have permanent magnets strong enough then so he used electromagnets for field coils. He routed all the current through the armature, which did not spin, through the field coils, which did. He had ball bearings where they were vital. He had his choice of steel...or silent, shellac-saturated rawhide for the planet gears. He had to use brushes and he chose to isolate the left and right sides of the wheel axlefrom the bike frame, to avoid making the bike frame a current path and parasitic risk, I guess (Someone else, please explain and correct me). He does not describe a battery because he does not propose a new form of battery. The French had more than one type of battery to choose from in 1896. The pasted-plate lead acid cell was invented in France but not all that well-developed in 1896. In 1896 the French were years ahead of all other nations with their automotive technology. They knew the internal combustion engine their people were improving would become the long-term power source for self propelled vehicles. Imagine the difficulty to sell an electric bike anywhere in 1896! Why, it would be laughed at! "How much does it have to weigh, you say?" The hub motor ebike, the any-emotor bike, had to wait until lithium ion chemistry to became cheap enough, to become any good in this real world. And that inventor doubtless knew it! Yet, he persisted, he persisted to file a patent, just-in-case!