Dual input cable for mobile phone - data/charging

[sinbrad]

Ok Guys,

I am after a cable that would allow my mobile phone to charge and transmit/receive data to my in car head unit with enough power to stop it running flat. I've looked around and found Y cables that allow two power inputs and one output but these seem to be for external hard drives etc. My problem is that my head unit doesn't give out enough juice to keep the phone charged if I'm using it for GPS etc. I want to be able to connect the phone to the head unit via the standard data cable but also inject a separate power supply thus giving the phone enough juice not to konk out. Is there such a thing? It must be USB

[legolamb]

Maybe a powered USB hub would work?

[sinbrad]

Nope, doesn't work with powered USB hub. Gonna have to think about something else as I've attempted to mod so many cables and it won't work!