I am looking for a car charger for my mavic which will work when my car is off (my current car 12 volt cig lighter is always powered on). I know the official one will not charge unless the car is on. I have read some good reviews on the cheap $20 one. But I just found this one popping up, I like it because it rotates, has a usb port, and shows the voltage. I have not seen any reviews on this to see how it works and if it works with the car off.