Rechargeable batteries are used in a variety of devices. There are several different types of batteries that use different technologies for different types of devices. Three main types of rechargeable batteries are 9 Volt, D, or AA and also AAA. But what to these letters mean and why are they different?

A 9 Volt battery is a rectangular battery used in small consumer electronics. Rectangular is a shape used for most batteries which are 4 volt or higher, up to 12 volt. All batteries are made of cells, but the cells in a 9 volt are connected in a series combination which makes the voltage rating of the battery the sum of the voltage of the cells.

D is another type of available rechargeable battery. It is cylindrical and 1.5Volt. D batteries are referred to as batteries, even though they are really just a D cell. As opposed to the 9 volt which is several cells connected, the D cell is simply one type of cell. D cells are used for a variety of electronic devices.

AA or AAA batteries are typically composed of alkaline. However, NiCd and NiMH are now available for rechargeable types and have higher capacity than alkaline. AA and AAA are used in handheld devices like remotes, digital cameras, model cars. AA and AAA hold the same amount of power, but AA has more lifetime, which is why it is larger.

All rechargeable batteries are referred to as secondary cells because they can be charged after they are drained. 9 volt, D, AA and AAA are all dry cell type batteries because they do not contain the wet lead acid as in the oldest type of rechargeable batteries. Buying quality batteries and charging them properly is the best way to get the most out of your money.