Nickel cadmium batteries are most often used for cordless drills and other cordless power tools. These rechargeable batteries have a long shelf life and can be charged and discharged over 1,000 times. Nickel cadmium batteries are the least expensive rechargeables and can be recharged in an hour. Because of its fast recharge time and durability, the nickel cadmium rechargeable battery is well suited to power tool usage. Nickel cadmium batteries work well under different temperature extremes.
The major drawback of Nickel cadmium batteries is low energy density which necessitates the need for more frequent recharging. Another negative for nickel cadmium batteries is the toxic chemicals they contain. Because cadmium is toxic to humans these batteries must be recycled rather than discarded. A European Union edict, 2006/66/EC, restricts the use of nickel cadmium batteries and the way they are disposed of.
Nickel Metal Hydride
Nickel metal hydride batteries are safer than nickel cadmium batteries because there is no cadmium inside. Instead, the anode is a metal alloy that absorbs hydrogen. These batteries are also sensitive to temperature extremes and lose charge quickly in cold temperatures.
Nickel metal hydride batteries cost more than nickel cadmium batteries but have a greater energy density and can be used longer between recharges. When worn out, nickel metal hydride batteries must be recycled because the anode contains cobalt.
The lithium ion battery offers advantages over nickel-based batteries, but has disadvantages too. With twice the energy density of nickel-based batteries, the lithium ion battery pack weighs less and works longer than nickel-based batteries. The lighter weight makes the drill easier to use for long periods, putting less strain on hand and arm muscles. Lithium ion batteries need to be recharged less often but have a much shorter shelf life than nickel-based batteries. Lithium ion batteries are also more expensive.
Because they are more durable, charge quickly, cost less and operate well under wide extremes of temperature, nickel cadmium batteries are an excellent choice for cordless drills and tools. Nickel metal hydride batteries offer longer time between recharges but have a shorter life than nickel cadmium batteries. Lithium ion batteries are lightweight and easy to use, but their short shelf life and high cost are negatives.