Works quite well but only for small devices if you want any time. With my gaming computer connected it estimates anywhere from 4-11minutes. The reason I'm giving it a 4 is because there was nil instruction in the manual on the battery connector on the back that needed to be plugged in prior to use. It appeared dead and when I returned it to the shop they didn't know either but when they got into their system there was a lot of big red warnings there. Would be nice to get those earlier instead of wasting an hour driving around.