I just purchased the Bracketron Universal GPS Charger. Bracketron Universal GPS Car Charger - eBay (item 190489706604 end time Feb-10-11 13:41:45 PST) It plugs into a cigarette lighter socket. This seller has reduced shipping when you buy more than one, so I bought 2. One for the car, one for my boat. The unit ships with 4 adapters: P1=Mini USB (which does *not* fit into the S7 USB port); P2=Garmin DC; P3=3.2 mm (fits the S7 like a glove); P4=4mm DC for TomTom devices. I used it briefly yesterday and it powered my in-use S7. Two oddities to note. First, the Bracketron website describes this device as powering up to 5 volts and 2.0 amps, but the packaging says 5 volts and 1.5 amps. Second, the website says the P3 adapter is 3.5 mm when in fact what ships is the 3.2 mm connector which works with the S7. I will power the Bracketron up and test the output on a multimeter when I find the time. What is up with the lousy/incomplete/incorrect documentation that comes out from so many companies???