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Everything you need to know about power tool batteries

Everything you need to know about power tool batteries

The average person spends a third of their life at work, another third asleep, and the remaining third untangling wires. Okay, that last one isn't true, but it does remind us how irritating wires, cables and cords can be, and that we should be grateful for the invention of the cordless power tool.

Thanks to the effectiveness of battery-powered portable tools, there is little need nowadays to use handheld tools that require a cord. However, despite the added portability and space-saving that cordless tools provide, the rechargeable batteries they rely on for power come with their own drawbacks.

Let’s take a look at the various types of power tool battery, their common features, and their pros and cons.

Characteristics of power tool batteries

Voltage: the higher the voltage, the more powerful the tool. In general, necessary battery voltage can be defined roughly as:

Light work: 7v-15v
Medium work: 12v-18v
Heavy work: 18v-36v

Cycle life: how many times the battery can be charged before losing its effectiveness or ability to transfer energy.
Charge hold: the energy stored in inactive batteries is released over time, but different batteries hold their charge better than others.
Run time: measured in amperage hours (Ah), this defines how long the battery will last before it needs to be recharged.
Memory effect: some batteries ‘remember’ a new charge capacity if they are not fully drained before being recharged. This may occur after repeated charges, and can effectively reduce the run time of a battery.

Power tool battery types

There are three main types of rechargeable battery for power tools: nickel cadmium (NiCd), nickel metal hydride (NiMH), and lithium ion (Li-Ion).

Nickel cadmium (NiCd) batteries

Though they are the oldest type, due to their long cycle life, robustness and lower price, these batteries remain in use.

Pros: durable, long cycle life, less expensive
Cons: heavy, lower run time than other battery types, suffer from memory effect especially if not fully drained periodically, not eco-friendly to dispose of
Cycle life: long, >1000 charges
Charge hold: medium, approx. 15% loss
Run time: low, 1.2 Ah - 2.2 Ah
Memory effect: high if not maintained properly – must be fully run down once a month

Nickel metal hydride (NiMH) batteries

NiMH batteries have a longer run time than their NiCd counterparts and are more environmentally friendly, but they are also more susceptible to loss in performance.

Pros: lightweight, good run time, moderate price, better for the environment than NiCd
Cons: temperature-sensitive, not robust - poor maintenance will reduce run time and cycle life
Cycle life: long, if properly maintained – store at between 0°C and 40°C, charge when it reaches 70%
Charge hold: low, approx. 25% loss
Run time: medium, 2.2 Ah - 3.0 Ah
Memory effect: medium, if maintained properly - must be fully run down once every three months

Lithium ion (Li-Ion) batteries

These are the newest type of battery, and the most effective, but also the most expensive.

Pros: excellent charge hold, high run time, lightweight, no memory effect
Cons: low cycle life, temperature-sensitive, expensive
Cycle life: short, up to 500 charges
Charge hold: high, almost lossless
Run time: high, > 3.0 Ah
Memory effect: none

With this information you should have a better understanding of how different types of battery can affect the price and performance of a tool, and will be able to make a well-informed decision on your next cordless power tool purchase.

Just think about the way that you’ll be using the tool, and what kind of battery would best suit that usage. For instance, if you’re expecting to use the tool only once in a while, you’d be best off choosing a reasonably priced one with a battery that holds its charge well, such as an NiCd battery.

If you have further questions about power tool batteries, don’t hesitate to get in touch or drop by our Kingsfold depot.