If the host computer for an USB device doesn't provide enough power for a device which has no dedicated power port, can I connect the power-only-plug of a Y-USB-cable to an other computer, an USB-charger or even a regular mobile charger? I'm afraid this could damage some of the devices.
Edit: The device in question is a USB Hard drive (Samsung S2 Portable 640GB (but on the back it's written to use 0.85A)) which is supposed to work whit just a single USB port. It did so well on a other laptop and whit some cables even on my actual net book back in Europe. But now in Malaysia it works only some times (I still try to figure out what the conditions are) and then it stops working after a while (maybe when it goes to power save mode). I heard from others their hard drives need one more power plug here in Malaysia to but can't imagine why…
Best Answer
Yes. You can get USB power from another source but it still might not work...
USB power is only +5 volts DC. And as long as you don't connect the inner data lines (which can cause other problems) you should be just fine getting your +5VDC from somewhere else. But if this is an iPod or something then it probably still won't work. And the reason that it might fail is because some devices like iPods require a minimum amount of current as well as possibly even certain signals like a 1.5VDC level on a data line, for example.
Frankly, you'd probably be better off getting a powered USB hub. As long as you don't try to get an expensive hub, like for USB-3 or something, you probably can find one for under $20 or even under $10. So is it worth the potential damage to another computer over what might not even cost a saw buck?! (It's your decision...)