The primary difference between heavy-duty batteries and alkaline batteries is the electrolyte they use to produce electricity. Heavy-duty batteries use zinc chloride as the electrolyte, while alkaline batteries use potassium hydroxide, an alkaline, as the electrolyte. A heavy-duty battery uses the outside zinc case as the anode, while an alkaline battery uses the zinc contained in a gel inside a steel case.
These differences in construction affect the power produced by the batteries. While heavy-duty batteries provide an improvement over standard zinc-carbon batteries, they do not match that of the alkaline battery. In low-drain operations, such as remote controls, clocks or radios, heavy-duty batteries are an economical option that performs well. However, as the power demand increases, the return on investment for alkaline batteries also increases. In hand-held games, alkaline batteries offer three times the battery life of a heavy-duty cell. Manufacturers of alkaline batteries also claim that some of their products have a shelf life of up to 10 years, while the shelf life of heavy-duty batteries is 3 years.
Both heavy-duty and alkaline batteries are primary cells. Manufacturers intend them for a single use without recharging. One of the problems with primary cells is that, regardless of the construction, the amount of power delivered decreases over time. Rechargeable batteries are secondary cells that begin with a slightly lower initial power output but provide a level amount of energy until the device drains them.