Batteries are available in 3  main types for use in cordless tools presently available on the market.   Manufacturers are constantly trying to improve the types of batteries available for the market, because the largest limitation of a cordless tool is of course its battery life and the amount of work you can get out of the tool per battery charge.  

BATTERY TYPES

Battery packs in power tools are constructed using either Nickel Cadmium (NiCD)  , Nickel Metal Hydride (NiMH) or Lithium Ion (Li-Ion) Technology.  

Nickel Cadmium

NiCD batteries have been used in tools since the first tools were produced.   It is a widely known fact that is you don't run your batteries flat before they are charged, after a while they begin to develop a " memory effect" which results in a loss of battery capacity and reduced lifespan of the pack, because once the memory effect begins, it will continue to develop, and no real way to reverse it.   NiCD batteries also are unable to be made with a capacity above 2.4Ah in the size that is useable for tools, and some feedback suggest that the 2.0Ah battery packs are quite often better than the higher rated ones.   The advantage to NiCD packs is that they have no real limit to their lifespan, and if treated perfectly (probably not really possible while still being used) will never lose capacity or develop a memory, although in real terms most battery packs will lose capacity by the time they have done 1000 charge/discharge cycles.

Nickel Metal Hydride

NiMH batteries are a newer development, and have really come into prominence  since digital cameras have become commonplace.   They are capable of being produced with a much higher capacity than NiCD Batteries, and some tools on the market presently have up to 3.5Ah Battery packs available, with larger to come.   NiMH also doesn't develop the memory effect in the cells so they don't have to be fully discharged before recharging.   The disadvantage to NiMH is that most manufacturers claims that after approximately 1500 Charge/Discharge cycles the pack will lose capacity rapidly and require replacement, and every time the cell is plugged into the charger that is 1 cycle off its lifespan.   So to get maximum usage out of the cells, it pays to run them until the pack is at least nearly flat before recharging.

Lithium Ion

Li-Ion Batteries are the newest development for cordless tools.   The technology has been in use for mobile phone batteries and portable computer for several years, but have only recently been adapted for the tool market.   These batteries are lighter than other types of battery packs and can therefore be made into higher voltage units.   They also do not suffer from the charge/discharge problems common to other battery types.   For more information check our Lithium Facts Page

Battery Ratings

The ratings on most batteries include a voltage and an amp/hour (shown as Ah) rating.   To simplify this slightly, the battery packs are made up of a group of individual batteries joined together in a row.   The Ah rating relates to the amount of power the batteries can deliver, if you have a 2.0Ah battery and do 1Amp worth of work with the drill, the battery charge will power the drill for 2 hours.   This is also useful for comparing similar drills, if 2 drills are 12V but one has a 1.3Ah battery pack and one has a 3.0Ah Pack, the smaller one is capable of 15.6W of work for 1 hour, the other is capable of 36W of work for 1 hour or the same work as the smaller one for 2.3 hours.   That can make quite a difference.

Battery Sizes

Nicd & NiMH battery packs are made of groups of c-sized batteries joined together.   This means for every 1.2V the packs increases, it must also increase by the size and weight of 1 extra battery.   If you are doing some light duty drilling at home, or at work, and only expect to maybe drill 20 holes a day into some materials then it's probably not worth buying an 18V drill just for the extra size and weight you would have to support, let alone the extra cost of the tool.   Li-Ion Batteries are made of cells slightly over the size of a AA battery that delivers 3.6V but less current.   This is where the weight saving comes from.   To read more about the way Li-Ion delivers the power needed check our Lithium Facts Page.

Replacing Batteries and Cells

Battery packs on tools do need to be replaced eventually.   Cadmium in NiCD batteries is highly toxic and makes its way from landfill all to easily into the water table and from there into drinking water.   Here at United Tools Albany we are a reclamation agent for most brands of battery tools, so if a battery is dead, don't throw it away, just drop it into our shop and we will organise for it to be taken care of.

Occasionally just 1 cell in a pack dies, and can be replaced.   Before you tear your pack open and just stick in any old battery that you've found lying around, the battery needs to be exactly the same as the others, any drop in Ah rating and the pack suffers, and dis-similarity in the compounds used and the cells may corrode and leak rapidly.