As technology improves, battery impact wrenches just keep getting better and better. However, there are still a lot of bad ones out there. If you’re in the market for a cordless impact wrench, you’ll want to make sure that you get a powerful enough battery, that it’s got enough torque for the job, and that you remember that you get what you pay for. The battery has always been the weak point for most cordless tools. Always being too heavy, and not providing enough power. Battery technology is finally catching up though, and cordless impact wrenches are starting to be a better option than their pneumatic counterpart. Some things to consider are Lithium Ion batteries (that are coming on most newer cordless wrenches) will last longer, and are lighter than the older Ni-Cad batteries.
Also, a more powerful battery (i.e. 18 volts vs. 14.4 volts) is not necessarily better. It is not uncommon for a more expensive, better quality impact wrench, with a 14.4 volt battery to be more powerful and longer lasting than a cheaper 18 volt wrench. This has a lot to do with the efficiency of the wrench, and an in-efficient wrench will lose a lot of power through the motor, instead of transferring it to the bolt that you’re trying to take off. This leads me into the next point that with cordless tools, you get what you pay for! This is not the type of thing that you want to go cheap on.
We are just now starting to get to the stage where cordless impact wrenches are actually worth using, and unfortunately that technology is still only with the more expensive wrenches. It will start to trickle down into the cheaper wrenches eventually, but it’s not there yet. Just keep in mind that you definitely get what you pay for! Another thing to consider is how much torque it has, and if your wrench will have variable torque control. With a new wrench you want to make sure it’s powerful enough for your hardest-to-get-off jobs. But if you’ll be using your new impact wrench for a bunch of different sized bolts, having a variable torque control can be great to ensure you don’t strip/round or over tighten your smaller bolts.impact wrench offers excellent info on this.
One more thing to keep in mind is that many cordless impact wrenches rate their torque as inch/pound, where most pneumatic wrenches are rated in foot/pounds. The conversion rate is 12, and if you see something in inch/pounds, you divide that number by 12 to get foot-pounds. So a cordless wrench with 1,950 in-lbs, will work out to be 162.5 ft-lbs. Battery impact wrenches just keep getting better and better, but if you are looking to buy one, you still have to be keep in mind the type of battery, how much torque there is, whether the torque is variable, if the torque is rated in in-lbs or ft-lbs, and also that you get what you pay for.