Cordless drills: How we test cordless drills
Hammer drilling tests
Drilling in concrete
We test how effective hammer drills are by drilling holes in concrete. We drill five holes with four hammer-drill bits, ranging in diameter between 6mm and 12mm. We aim to drill holes to a depth of 50mm. We record how far into the concrete they get and how quickly they get there.
Rotary drilling tests
Drilling in wood
We drill five holes with a 6mm drill bit to a depth of 40mm into beech. We record how quickly the drills reached the required depth.
Drilling in metal
Using a 6mm drill bit, we drill another five holes to a depth of 5mm in steel and we record how long it takes each drill to sink the holes.
Drilling in sandstone
Five holes are drilled using a 6mm drill bit in sandstone – we drill to a depth of 30mm and we record the time taken to drill the holes.
Screwdriving in wood
We drive screws of various sizes (3x40mm, 6x80mm and 8x80mm) into pine and we record the time taken and the depths reached in the wood.
Screwdriving in metal
We drive four screws into steel to a depth of 5mm and we record how long it takes to drive the screws home, and how deep they get in the steel.
Battery life tests
Full charge test
We fully charge each drill’s battery and then see how many holes can be drilled in sandstone. We then use another fully charged battery and see how many screws can be driven into pine. The best drills we’ve tested can drill more than 100 holes and 150 screws. The worst we’ve seen can manage only around 40 holes and 40 screws.
Quick charge test
We charge each battery for 15 minutes and then repeat our full charge test. The best drills we’ve seen can drill around 50 holes after a 15-minute charge, the worst will struggle to drill more than one or two.
Losing charge test
We fully charge a drill battery and then leave it for a month. We then measure the amount of charge left in the drill. The best drills we’ve tested will retain more than 95% of their original charge. The worst will lose more than 60% of their original charge in four weeks.
We test the durability of a drill’s motor by running it through more than 2000 cycles of drilling, resting and screwdriving. In all, this takes around 33 hours and is equivalent to about ten years of DIY use.