I received this as a gift last Xmas. I charged it up for the required 12hrs then tried to use it to inflate my tires. However, the socket doesn't seem to grip the valve properly. No matter I thought, I can still use it as a jump-start in an emergency. I'm glad I've never been stuck, as I checked the battery about 3 months later, and it had gone flat, but not only that, it will not recharge! It also has a terrible build quality, with sharp edges, ill-fitting covers and an accessory door that will not stay in place. This may be the crappiest product I have ever encountered.