Primary or disposable batteries include standard alkaline and the newer lithium.

Secondary or rechargeable batteries include: NiCd, NiMH, and Li-ion.

NiCd or nickel cadmium batteries were the first type of rechargeable on the market.  These batteries which still are used for certain applications contain the very toxic cadmium.  Newer NiMH batteries which are less toxic and have a bigger capacity have reduced the need for these batteries.  These are available in AAA-AA-C-D-9V sizes.

NiMH or nickel metal hydride batteries were the next rechargeable introduced.  They are more suitable for high drain devices such as MP3 players, video games, and digital cameras.  Technological advances have made the use of NiMH batteries safer and easier to use than older NiCd batteries. These are available in AAA-AA-C-D-9V sizes.

NiMH Low self-discharge(LSD) batteries are the newest incarnation of the NiMH battery.  Just like alkaline batteries these batteries can be used right out of the package as they hold a charge much longer than previous NiMH rechargeables- they only lose 15-25% of their charge a year.  These batteries are available in AAA-AA-C-D sizes.

Li-ion or Lithium-ion batteries are the newest and most efficient of the three rechargeables.  These batteries have the advantage of being suitable for high drain devices and a long lasting charge when not in use.  They are also very light in weight and fast to recharge.  These batteries can be found in digital cameras, phones, computers, and MP3 players.  They do not come in the standard sizes AAA-AA-C-D-9V.

Self discharging
Rechargeable batteries all lose their charge when either stored or in devices that get very low use. This is known as the self discharge.  NiMH batteries have the highest, losing 30% of their charge a month.  NiCd have a rate about 10% a month, and Li-ion are at 5%.  New low self-discharge NiMH batteries have the lowest rate at only 25% a year when stored!  It is recommended that for emergency use such as smoke alarms or emergency kits where the battery will be stored for long periods of time, disposable batteries are more suitable.

Charger Types

Plug-in: This is the most common type of battery charger which there are different models that can charge single batteries or multiple batteries at the same time.
Solar: These are becoming more popular and come in different solar cell sizes.  These can be found through an internet search or using the links found on this website.
USB: This new type of charging system allows the user to charge directly through the computer USB port.