Before you buy a cordless drill, or at least after you have already bought it, you should test it to see if it is good or not. And testing a cordless drill does not consist only of making a hole in a wall. You have to test it in different surfaces, depending on what kind of drill it is and for different things, for the same reason. You can also check http://www.onelastreview.com/best-cordless-drill-reviews for more details.
Fortunately, there are so many videos online that tell you just what you need to do in order to test your drill and how it is supposed to react so that you know whether it is good or not.
For hammer drills you can tests them by making different holes in concrete. This is the type of drill that is used for harder material such as concrete, and will not be very useful in other, softer materials. That is because of the power with which it works and how it pounds the material so that the drilling goes even better and to add to the power of the tool. The way in which you can test this type of drill is by making several holes with different drill bits and see how far they go in and how much time it takes them to get there. This is an easy task, but you might also have to put some muscle into it, since the material that you are working with is a very hard one.
Then there are the rotary drills, which can be tested in either wood, metal or some softer type of rock, such as limestone. These drills are very powerful as well, but they are meant for softer materials than concrete. When you test these types of drills, the method is the same as the one before, and it`s just the material that is different. Also, the depths at which the drill bits have to reach are different as well, since the materials are softer, so the drill should go in deeper and faster.
Then there is the screw driving test, which can be done in either wood or metal. It is basically the same as the ones with the drill bits, only this time you will be using screws and they will remain there. You have to test how well the screws are imbedded into the material, how fast they got in there and how stable the machine was when you put the screw in.