How to Choose an Electric Screwdriver
Cordless Screwdriver Options
There are three basic options to choose from when buying an electric, or cordless, screwdriver. Which one will make the best choice for the purchaser depends a great deal on what use the tool will be put to. Within each option is also the question of battery voltage as that will play a large part in how much power the screwdriver has and how long the battery will last.
The basic groups of cordless tools that function as a screwdriver are the cordless screwdriver, the cordless drill driver and the cordless impact driver. Each has its pros and cons and are best at different tasks. The cordless screwdriver is a good choice for very lightweight work, or perhaps driving screws into threaded holes. The cordless drill driver is probably the most useful power tool in the home, and will drive a variety of screws, but is not designed specifically for that task and it is very easy to strip out a phillips head screw. The impact driver is absolutely the best choice for driving lots of screws or for driving large screws. It is the most powerful, the batteries last longer and it doesn't strip screws out nearly as badly as the other two choices, but it is also a dedicated tool and not much good for anything else.
As a professional electrician, I use all of these cordless tools on a regular basis, and have extensive experience with various manufacturers as well. The recommendations below reflect that experience although few homeowners will ever require the heavy usage of their tools that I do on a construction site.
The Electric Screwdriver
These cordless tools (the term "electric" is generally reserved for a plug in tool) are primarily intended to be used as a simple screwdriver although sockets are available and can be used in the smaller sizes up to about 3/8". Beyond that, these small lightweight tools simply don't have the power to tighten a nut or bolt.
Electric screwdrivers all use a ¼" hex bit that fits into the screwdriver with a quick connect fitting, and there are a wide variety of these bits available as well. Bits can be a straight blade, a phillips tip, square tip, torx or star as well as many other types. There is certainly no lack of choice in the type of bit, and they are readily available. Don't shop for the cheapest bits around, as the quality of the steel will be very poor and they will break quite easily. A cheap phillips bit, for example, likely won't last through the first screw. A kit such as is shown below is recommended, with a large number of bits and several of the more popular ones as they do wear out. This kit comes with the added bonus of a hand ratchet, and that can be handy. Along with bits, I like to have a magnetic bit extender as well as it makes changing bits very easy whether in a screwdriver or drill and it makes the use of shorter bits easier as well.
Battery voltages range from 2.4 volts up to a heavy duty 7.2 volts. A word of caution here; if your expected usage is to drive screws into wood, a 2.4 volt or even the more common 3.6 volt will not be satisfactory. Most 3.6 cordless screwdrivers will drive a small screw a short distance into wood, but that's about all. Even the heavy duty 7.2 volt screwdriver pictured below begins to bog down with a #8 screw at about ½" into a 2X4. As an electrician I use that cordless screwdriver to install outlets and switches, not to put screws into wood - there are better tools if that is the intent.
A nice feature that the better cordless screwdrivers have is the ability to bend in the middle. There are times when a straight tool is more convenient and others when an angled configuration works better. If you expect to use the screwdriver a lot, consider paying the extra for that convenience.
The Dewalt screwdriver example below is the one I use professionally and is recommended.
Screwdriver bits from Amazon
Cordless Screwdrivers from Amazon
Cordless Drill Drivers
The next major group to be considered are the drill drivers. These are cordless drills that have additional features of a variable speed trigger and a clutch built in. The variable speed allows the drill to operate at slower speeds and is often valuable when driving screws. The clutch allows the user to set the maximum torque the drill driver will apply and helps prevent stripping or breaking screws - valuable as any good drill will twist smaller screws right in half if given the chance.
A drill driver does not have the quick change mechanism for bit changes but rather has an ordinary drill chuck. This does not mean that it cannot use the popular screwdriver bits, though - the chuck readily accepts these bits. The magnetic bit extension is a must here, for ease of changing bits.
The plus of a drill driver is, of course, that you will also have a drill - probably the most useful power tool in the home and if you don't already have a drill I recommend a drill driver for driving screws. This again brings up the question of battery voltage. If a good deal of drilling is expected, don't go with less than a 12 volt drill and an 18 volt is much preferred. At the same time, the newer 24 volt and even larger batteries are unnecessary for home use - they mostly provide increased battery life and not more torque or power. The newer lithium ion batteries are very nice - lightweight while lasting longer than the older NiCad batteries. A drill driver with two batteries will suffice for very nearly anything the homeowner is likely to do.
Top of the line drill drivers include those from Milwaukee and Dewalt, but they are often quite costly compared to other brands. Most homeowners will be quite pleased with a Ryobi, Porter Cable or Makita brand, and I'm seeing more of these even on construction job sites. They don't tend to last quite as long, but the price usually more than makes up for that. Other more uncommon and very cheap brands will (usually) work, but life expectancy is not good for many of them. A homeowner that only rarely uses their drill driver may be happy with a $50 drill, but anyone using it very much will quickly become dissatisfied.
I recently purchased a large kit from Porter Cable with several cordless tools in it, including the drill shown below, for my home. It has the ½" chuck that I require (and I suggest that you do, too) and has performed well. I recommend it for a homeowner wanting a good quality tool, but not necessarily a professional quality.
Cordless Drills from Amazon
Cordless Impact Drivers
Cordless impact drivers are the newest addition to cordless tools in general and they are fantastic at driving screws. Most useful for heavy duty screw driving, they do not have a clutch and can twist even a large screw in half without much trouble. Impact drivers (as opposed to an impact wrench) use the same hex bit quick change system as the cordless screwdrivers do. Although a few drill bits are manufactured for this system the impact driver is not a drill and does not function well as one.
While a drill driver will drive a large screw, it often strips out the Phillips head of the screw doing it. The impact driver does not have that problem to nearly the same degree; the impact action does a much better job of driving the screw without stripping the head. In addition it does not require near the power as the drill driver, and batteries last a long time before needing recharging.
If you are driving lots of screws, or large screws, (building a deck, maybe, with deck screws instead of nails) the cordless impact driver is the way to go. Nothing else can match them at heavy duty screw driving, they are lightweight compared to a drill driver and one battery may drive a hundred or screws or more.
Recommendations here are similar to the driver drill; Dewalt and Milwaukee make excellent tools, while Ryobi, Porter Cable and Makita are usually a little less costly and quite acceptable for homeowner use. Lithium batteries are always nice, but hardly necessary here as impact drivers use so little battery anyway. If you already own a name brand cordless drill, chances are good that you can buy a bare impact driver, without batteries, charger or the price that comes with those items, that will work with the batteries you already have. The Porter Cable impact driver shown below came in the kit I purchased, and has done an excellent job around the home. I haven't owned long enough that I would recommend it for daily heavy duty use, but for the home it is an excellent choice.
One word of caution; make sure you are looking at an impact driver and not an impact wrench. The driver is used for driving screws and tightening small nuts and bolts, the wrench is what the tire store uses to put your tires on with.
Cordless Impact Drivers from Amazon