DeWalt makes a couple different types of batteries, including lithium ion batteries and nickel cadmium batteries. These batteries are referred to as "secondary cells," which indicates that they are rechargeable.
DeWalt offers an 18-volt "XRP" model lithium ion rechargeable battery as well as an 18-volt "XRP" model rechargeable nickel cadmium battery. Their "Compact" series of batteries includes an 18-volt rechargeable lithium ion battery and an 18-volt rechargeable nickel cadmium battery.
The 18-volt models of Dewalt rechargeable batteries are designed to different weights. Their 18-volt nickel cadmium batteries are generally heavier than their 18-volt lithium ion counterparts. The lithium ion XRP battery weighs 1.5 lbs., while the Compact lithium ion battery weighs 1 pound. The nickel cadmium XRP battery weighs 2.4 lbs., and the nickel cadmium Compact battery weighs 1.7 lbs.
The XRP lithium ion battery takes one hour to charge and can be recharged about 2,000 times. The Compact lithium ion battery takes 30 minutes to charge and can be recharged about 1,000 times. Both the XRP and Compact nickel cadmium 18-volt batteries take an hour to charge and can be recharged approximately 800 times before they need replacing.