ea battery is different but most common is 1.5AAA, 1.5AA, 1.5C, 1.5D, and uses alkaline, and alkaline is not rechargeable, whereas a cell batt. uses nickle, or lythium metals. For the most part you put about 5 together to get the output power of 7.5volts and of course then you have a 9v batt. the name speaks for itself. And then you have a car battery some sealed lead acid and some you have to use distilled water, but each get charged with an alternator which creates the ions in the battery, as long as the battery has fluid, if it runs dry then the ions cannot be produced and you have a dead battery. As for flashlight ratings being a single cell to a 4cell, it is what it says. Single cell is one battery, up to say 4 cell, which is 4 batteries, and if each is a 1.5v then you just multiply by 4. I hope it makes sense cause I don’t have the any idea what I’m saying. So I hope someone or the bunny writes and gives the answer you are looking for.