Different types of batteries are made using various chemical compounds. They also have different voltages and different capacities.

Rechargeable alkaline batteries are relatively inexpensive. The charging time for this type of battery ranges from three to 12 hours. They are generally used for small electronics like radios and other portable devices.

A nickel cadmium battery is heavier than an alkaline battery, but provides more run time. A large number of cells also increases the weight and run time of a battery. Therefore, an 18-volt battery will run considerably longer than a 9.6 volt battery because the 18-volt battery has twice the cells than the 9.6 volt. The higher voltage batteries are generally found on tools such as a cordless drill or a circular saw.

A battery charger works by accepting voltage from a standard outlet. The amount of charge that is transferred to the battery depends upon the 'brain' inside the charger. A large battery charger typically has a more efficient brain than a smaller one. Charging a battery creates heat, so it's important to keep them cool.

An advanced battery charger will have a fan that takes the heat away from the battery. The charge takes approximately 20 minutes. It has a sensor that lets you know if the battery is defective. This type of charger creates what is known as a trickle charge, which won't hurt the battery or cause a memory defect.

A nickel metal hydride battery is more expensive than a nickel cadmium battery, but the nickel metal hydride provides 20 to 30 percent more run time. There is no significant weight increase but are more expensive. They are not as common as the nickel cadmium.

Lithium ion batteries use half as many cells to get twice as much power as other batteries. That means that it provides twice the run time using a battery half the weight of a comparable nickel battery. Also, lithium ion battery doesn't run down slowly, like a nickel cadmium battery. This battery continues at full power until the battery runs out.