Technical development, material and production costs of rechargeable batteries are high.
Batteries are very economical in terms of electricity consumed and this is a benefit for the user.
Most batteries should last for at least 1000 charges which represents excellent value and on average use this is around three years subject to the right storage conditions.
Batteries are rated in voltage (V) and storage Amp Hours (Ah). The amount of time that working voltage is maintained is related to the work that a battery will complete and this depends on the application. Under a heavy load the motor will draw more amps, quickly reducing the batteries capacity versus a light load. As a guide the number large holes can be counted in tens while small screws in hundreds.
Batteries are rated in various Amp Hours. A 2Ah battery will deliver 40% more run time than 1.25 Ah, although this is reflected in a higher cost.
The majority of cordless chargers require a uniform current supply in order for the sophisticated electronics to operate. Under these circumstance maufacturers tend not to offer 110v chargers, as they do not work on generators.
The majority of power tools have a brush motor; periodically the brushes need to be replaced. Cordless tools are no different although in the majority of circumstances the brushes in a cordless motor cannot be replaced, resulting in the replacement of the complete motor.
DeWalt though have developed a motor which is used in the majority of it's cordless tools that allows for the brushes to be replaced incurring little cost.
With regards to batteries and chargers these are generally non-serviceable due to the make-up.
Generally the battery will benefit from being fully run down before recharging in order for the cells to balance themselves out. If one cell still has some charge left the rest will stop taking charge when the first cell is full. It is always advisable to fully run down a new battery before the first 5-6 re-charges as this helps to increase it's capacity.
NiCd batteries have been used in cordless tools for nearly forty years proving to be very reliable and effective as a means of cordless energy, due though to environmental and technical developments there is a general move towards NiMH. Although slightly more expensive NiMH offers improved capacity in Amp Hours (Ah) delivering a longer run time proving more cost effective. As they become more widely used their technical development will also improve.
The voltage of a cordless power tool is relational to the power the tool can deliver; this is also reflected in the energy the tool will consume. Battery technology has allowed for the development of higher voltage tools in relation to their run time.
A higher voltage tool will not only deliver more power resulting in a greater capacity, enabling the job to be done quicker. The only negative side is an increase in tool weight due to a larger battery.
The majority of cordless tools are supplied with a 1-hour fast charger and two batteries, this allows for one battery to be on charge while the other is being used. In some circumstances a faster re-charge time may be required dependant on the application, thus a 15-minute ultra quick charger is available as an accessory.
If a battery is regularly recharged before it is fully discharged it can cause an imbalance in the battery cells, which would result in a lowering of capacity; this is often referred to as 'memory'. Some chargers are now designed to help prevent this.