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Everything you need to know about power tool batteries

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Power tool batteries in a circle around Badaptor

Buying the right power tool battery can be a tricky business. Navigating all the different battery types, voltages and ampere-hours can be tough, and you need to make sure you get the right battery for your tool. So we’ve decided to cover the basics of power tool batteries, so you can make an informed decision next time you’re looking to buy.


Different battery types

Before we look at battery power and runtime, we first need to know the difference between the types of battery currently on sale.

The most widely-available battery is lithium-ion (Li-ion). This battery technology is used by all the main power tool brands. Lithium-ion batteries have overtaken other battery technologies in recent years thanks to their smaller size, energy efficiency, and slow self-discharge rate. For those that don’t know, self-discharge rate is the speed at which the battery will discharge when it’s not in use. The only negative to be aware of is price, as lithium-ion batteries can be double, or sometimes triple the cost of other batteries.

Nickel Metal Hydride (NiMH) batteries are also widely used. These batteries are considerably cheaper than lithium-ion batteries and can provide greater current to high-power tools. However, these batteries suffer from a higher rate of self-discharge and are susceptible to memory effect.

If you’ve never heard of memory effect, it’s a condition where a battery will hold less charge than its maximum capacity. If the battery is consistently charged when it’s not completely flat, the battery will remember the point at which it was charged and set that point as its new capacity (almost training your battery to hold less charge).

If you own an older power tool battery, there’s a good chance it will be a nickel-cadmium battery (NiCad). These batteries have been phased out over the last 10-15 years due to their susceptibility to memory effect, low capacity, and difficult disposal (they contain cadmium, which is toxic and damaging to the environment).


Battery voltage determines the overall power the battery provides. You’ll find that smaller tools like hand torches or electric screwdrivers will only require a 12V battery to run. Larger and more demanding tools may require anything between 18 and 40V. It’s therefore important to check what battery is required when purchasing new tools.

The most common voltage for handheld power tools is 18V (which, coincidentally, is also the voltage that Badaptors work with). This voltage provides a good balance between power, cost and battery size.


You may have seen the letter “Ah” on your power tool batteries. Ah stands for Ampere-hour and indicates the amount of charge a battery can provide in one hour. For example, a power tool will be able to draw 5 amps continuously for 1 hour with a 5.0 Ah battery under ideal conditions. However, it’s worth noting that this number is only a base estimate as, 99% of the time, the battery will not be under ideal conditions.

If you want to learn more about ampere-hours and why a 5.0Ah battery may outperform a 2.0Ah battery, check out the “Out of the woodworks” blog post.


When buying new tools, always read product descriptions to make sure you have the correct battery for the tool.

If you want some tips on how to look after your power tool batteries, we also have a handy blog post dedicated to keeping your batteries in good health.

But before you start buying new batteries for your tools, why not see if you can save money with a Badaptor first? With a Badaptor, you can convert your 18V batteries from DeWalt, Makita, Milwaukee, Bosch Professional, Ridgid or AEG to work with all the 18V tools in the Ryobi One+ range.

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