look at the size of the windings , the width of the case and U can see that it is not and never has been designed for breaking lug nuts loose, it is great for running them on and off after loosening and then they need to be tightend after that also,I absolutly LOVE mine !! You should feel how tight they should be, this could take practice no one can tell you how to feel it,..it only runs on 24 volt, it would need to be 220 !!!!!! and a bigger winding also.....it would be a miracle gun to be that size and only run on 24 volt , now it could be done but would be... ..bigger...and gear reduction...as for running with the engine off, I am sure U know what happens if the headlights are left on when the truck is off, its the same thing, batteries only hold so much juice, How new are your bats and are they the correct size for your truck?? there are plenty of times that the truck can be off for a quick burst, But u are loading the batts ,and will strain them if you are only running short stops, they may not be getting enough engine time to recharge, then they will sulphate by staying low and your bat life will shorten and then U will say your bats are junk, im just saying because it is as true for me as anyone else, most failures are human error, and they can start in the smallest places, these are the things u need to think about when draining your bats... I agree about electric impacts, the ones that run on 110 are just that weak . it would be quite a tool to run on so little power and do what most think they can, or a commercial suggested they could reality is almost always much different...