Cordless impact wrenches, which are battery powered, are becoming more and more popular everyday. Most of the competitive ones use an 18volt battery that supplies power to a 1/2 drive, electric impact gun. The principal is the same as the air impact gun, only a different power source is used. The cordless impact gun offers you a good amount of power and reliability along with portability.
The cordless guns are great in all but they aren’t near as powerful as a good air impact. When it comes to fields like mine, the automotive industry, you find yourself needing a lot of torque. Suspension components are a great example. Sometimes those nuts or bolts are extremely tough to break and the cordless will just bog down on it. I then pull out the handy air gun and zip it off with no problem. Along with good power, the air impact wrenches are just more durable and offer continuous power all day long. That is of course if your air compressor is working.
So you can see the cordless impact wrenches have some great benefits and I find them really useful in the shop. Instead of connecting an air hose to my beefy air gun, I just use my cordless to run up lug nuts and then tighten them down with a torque wrench. The same thing goes with other components on the car. If you need to zip something off or on real quick it’s definitely a time saver. The only major draw back is your limitations with the power. This is why I still have my beefy 1/2 air impact wrench.