When you think about how to buy batteries, there are several factors to keep in mind.
First, consdier whether you want single-use or rechargeable batteries. Single-use batteries are best used in medium- and low-drain devices, such as toys and clocks. Rechargeable batteries are ideal for heavy-drain devices such as digital cameras and cordless power tools.
You'll also have to think about what type of batteries you want. Alkaline batteries can be either rechargeable or single use and can be used in both high- and low-drain devices. Lithium batteries are lighter in weight, perform well at low temperatures, and have a shelf life of 10 years or more. Lithium ion batteries are the lightest weight rechargeable batteries and have a long shelf life and high-energy capacity, so they're ideal for cameras and camcorders.
Nickel cadmium (NiCad) batteries have a great cycle life, which makes them perfect for devices that use a lot of power quickly. For heavy drain devices that are used often, such as remote control toys and digital cameras, Nickel Metal Hydride (NiMH) batteries are a very cost effective rechargeable battery. And for low drain, low power devices such as remote controls and smoke detectors, carbon zinc batteries are very economical.