Orico A3H4 4 port USB Hub
This hub has a 12V input (and comes with a UK or EU 2.5A mains adapter). I've had a look at the components inside and it should be good for up to 20V from batteries or other sources on a standard 2.1mm DC barrel connector.
It'll power things like tablets computers, phones etc without a host machine being plugged in and can supply up to 2.4A per socket.
Solid Aluminium casing 100mm x 50mm x 50mm