Battery drills are versatile and they free you from the nuisance of a power cord. But they do have limitations – for really tough tasks you do need a mains-powered model.

Here's what to look for in a cordless drill:

• 1. Gearbox: Always buy a drill with a two-speed gearbox. In high gear (0-approx 1200rpm), the tool spins fast enough for quick drilling; and in low gear (0-approx 400rpm) you get controllable and grunty screwdriving.You change gear using a slide or rotary knob – so make sure this operates smoothly and without excessive force.
• 2. Keyless chuck: Look for a sleeve that gives a good-sized grip, without sharp ridges or grooves. Look for a chuck that can be tightened or loosened with one hand.
• 3. Chuck size: This limits the size of drill that the chuck can hold.
• 4. Torque limiter/clutch: Lets the drive slip once the set torque is reached. Useful for flush-driving countersunk screws. The final position locks the drive for drilling.
• 5. Handle: A rubber insert will cushion vibration and increase grip.
• 6. Variable speed trigger: The more you squeeze the trigger, the faster the drill goes. Look for a smooth easy-squeeze action.
• 7. Hammer action: Substantially speeds the drilling of masonry by vibrating the drill-bit in and out as it turns. Requires a lot of power. Usually found only on higher volt (18+) drills.

Other features

• Spare battery: A spare keeps you working: one charges up while the other is in use. Li-Ion batteries are lighter and more environmentally friendly than the older NiCad ones. We expect to see Li-Ion batteries slowly displace NiCads.
• Charger: A one-hour charger lets you recharge during lunch – and even get a substantial top-up during a shorter break. One-hour chargers pump quite a heavy current into the battery, which causes heating. Make sure the charger has protection against overheating .
• Wrist strap: Handy and safer when working in high places.
• Warranty: A trade-use warranty tells you about the maker’s view of the tool: it suggests the drill has been better constructed and is more durable than DIY versions.
• Voltage: Choose a lighter and lower-voltage drill for light-duty work, especially if you’re using the drill for long sessions or for overhead work. Choose a higher voltage for heavy-duty work.
• LED light: Lets you see what you’re drilling in dark areas.
• Speed range: A range of high speeds is more suitable for drilling smaller diameter holes (up to around 5mm in metal and 10mm in wood) while a low-speeds range is for larger diameter drilling and driving screws.

18-volt cordless systems

Several manufacturers sell a range of compatible 18-volt tools. This means tools such as torches, circular saws, grinders, jigsaws and others can use the same battery and charger system. The battery and charger make up a large percentage of the cost of a cordless tool – so this is a good way of maximising your investment.