what-are-the-different-types-of-cordless-power-tool-battery

What are the different types of cordless power tool battery?

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There are a lot of different variations of batteries for cordless power tools because of all the different manufacturers and no universal battery. It can be daunting seeing the huge range of cordless power tool batteries on the market but it’s actually much simpler than it seems. They can all be grouped into one of three main types and each cordless power tool manufacturer produces batteries and chargers to fit their products only, which means you are limited by your tool.
Nickel cadmium, nickel metal hydride, lithium ion (NiCd, NiMH, Li-ion) battery types. The three types of battery all work on the same principle (see How does a cordless power tool battery work?) but have different ‘chemistries’. They are nickel cadmium (NiCd), nickel metal hydride (NiMH) and lithium ion (Li-ion) batteries.
Voltage and battery capacity of a rechargeable battery for a cordless power tool Voltage and battery capacity are the other main variations between batteries. These are further discussed on the page  What cordless power tool battery sizes and weights are available?

Nickel cadmium

Nickel cadmium batteries work well when they are used regularly. Nickel cadmium (NiCd) rechargeable batteries are very durable and are ideal if you need to use your batteries for regular, intensive work and every day. They respond well to being repeatedly charged and then used up. Leaving them in chargers and only occasionally using them shortens their service life.
Battery charge/discharge cycle. Some battery types last for over 1000 cycles like the nickel cadmium battery (NiCd). They can be recharged over 1,000 times before their performance level starts deteriorating.
Nickel cadmium NiCd rechargeable batteries work well in cooler weather too. They can be recharged and used at lower temperatures than the other chemistries, with fewer negative effects on the battery.
NiCd nickel cadmium batteries will discharge during storage but not as much as NiMH. NiCd batteries self-discharge (gradually lose charge even when they’re not being used) during storage but not as quickly as NiMH batteries.
NiCd nickel cadmium rechargeable batteries are bigger and heavier than the other battery types. Of the three types, NiCd batteries have the lowest energy density which means that to produce the same power as a NiMH or Li-ion battery they have to be bigger and heavier.
NiCd nickel cadmium rechargeable batteries need to be fully discharged and then charged again to prevent memory effect. They also need to be regularly drained of charge and then charged again to prevent ‘memory effect’ (see How to prime a nickel-based cordless power tool battery) which stops the battery working properly.
NiCd nickel cadmium batteries contain toxic metals that need to be disposed of carefully. Disposal of NiCd batteries is also an issue as they contain toxic materials which damage the environment. The best option is to recycle them.

Nickel metal hydride

Nickel metal hydride is smaller and lighter than nickel cadmium rechargeable batteries. Nickel metal hydride (NiMH) rechargeable batteries’ biggest advantage over NiCd batteries is that they offer up to 40% higher energy density. This means they can be smaller and lighter but still provide the same amount of power. However, they are not as durable.
High temperatures damage nickel metal hydride NiMH rechargeable batteries. They are best used for lighter work as high temperatures and heavy use can decrease the service life of the battery from 300-500 charge/discharge cycles to only 200-300.
Memory effect is not as much of a problem for nickel metal hydride NiMH rechargeable batteries as it is for nickel cadmium. Although NiMH batteries need to be completely discharged once in a while, they are not as susceptible to memory effect as NiCd batteries.
Nickel metal hydride rechargeable batteries are less damaging to the environment NiMH batteries contain only mild toxins so are safer for the environment.
Nickel metal hydride NiMH rechargeable batteries need a longer charge time than nickel cadmium. They need a longer charge time than NiCd batteries because they heat up easily, which can damage them. They also have a self-discharge rate that is 50% higher than NiCd batteries.
Nickel metal hydride NiMH rechargeable batteries are more expensive than NiCd nickel cadmium. NiMH batteries are about 20% more expensive than NiCd batteries but are often deemed worth it for their higher energy density.

Lithium ion

Ions are easily formed from lithium metal in li-ion batteries for cordless power tools. Lithium is a lightweight metal that easily forms ions (see How does a cordless power tool battery work?), so is perfect for making batteries.
Lithium ions are the most expensive but probably worth it in many ways. Lithium ion (Li-ion) rechargeable batteries are the most expensive cordless power tool batteries but they are very small and lightweight with an energy density twice that of NiCd batteries.
Lithium ion rechargeable batteries are not affected by the memory effect which means they can be charged from any level of charge. Also, they don’t require much maintenance because they aren’t affected by the memory effect.
Lithium ion rechargeable batteries do self-discharge but can last much longer in storage in comparison to nickel batteries/ Although they do self-discharge, the rate is less than half that of NiCd batteries. Some Li-ion batteries can be stored for 500 days without needing to be charged on the following use.
Lithium batteries age fast than nickel rechargeable batteries. On the other hand, they are quite fragile and require a protection circuit that monitors voltage and temperature to prevent damage to the battery. They also age quickly, their performance being noticeably reduced after only a year.