Instructables

Do some usb power adapters supply 6.5 volts?

I took a 12 volt usb car usb adapter apart and wired it to a switch and a panel mounted female usb plug.  The power supply is outputting 6.5 volts.  This has me worried because I thought USB power was always 5 volts.  Maybe once I plug something into it the voltage will automatically change to a the right voltage and current required by the device.   

Also, this adapter says it is only compatible with Iphones.  Does that mean anything else usb powered would not work?

this is the adapter

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220702089964&ssPageName=STRK:MEaWNX:IT#ht_2128wt_1141

thanks

it hardly supplies any volts because it is used to transfer infromation and data stored on your computer through to it.
it may put voltage or current through it if that's the devices main power our charging source if not then there is most likely no voltage i could give you a better awnser if you told me what device you're using
NachoMahma4 years ago
.  Your adapter is probably not very well regulated. Volts out will probably drop to closer to 5V when you put a load on it.
This is most likely correct, many (if not most) chargers hover a little above voltage when unloaded. Shouldn't be an issue. If it puts out voltage without being connected to an iPhone, then it should work ok with other devices unless they demand something in particular. Some USB charging devices intentionally demand "their" charger so that you have to buy a replacement charger from them. If it charges plugged into a normal USB port without drivers (i.e. all it needs is a USB port with +5 and GND connected) it should work.