Bacpac.
For the vehicle, I use this 12V to USB adapter which can also be used for any other USB devices.
AH HA!! I found it! The kids bought one of these to charge their devives on a family road trip in the summer. They've long since forgotten about it but, as I was digging in the garage for a tent for our Scout group's Santa Claus Parade float, I found it. Why it was in the garage I do not know, but it's mine now!