I got the Milwaukee 18V and love it. I also have the Viair and don't use it anymore because you have to pop the hood and hook it up to the battery. While the Milwaukee is larger, it's just so simple to pop a battery in, weighs about 5 lbs and it's pretty fast.

I have one you can plug into a cigarette lighter type outlet in the truck.

This has saved me a couple times now. It has a jumper, alternator tester, battery tester, LED lights, usb charger, and air pump. Kinda bulky though.

Those lithium batteries hold a charge for months and months. I keep two batteries in the toolbox; I check them every six or eight months. They've always been well over 3/4 charged. I've aired up all four tires on the RV to 60psi and not used 1/4 charge. I used the impact to change a flat on the daughter's car on the side of the freeway and hardly used any charge at all. My buddy aired up the rear tire on his big Kubota tractor with my Ryobi. It took a while, but he still had plenty of battery left. He got one right after that.