Safe to charge USB devices while doing other power-consuming tasks?

Question

I just recently got an iPod, and I completely forgot that without an adapter you have to hook it up to your computer by USB port to charge it, sync, etc. I currently have it plugged into the front USB ports (there are some back ones, but I mostly use those for keyboard/mouse) and just sort of hanging there (it's an iPod shuffle and the charger cord is really short to do anything else with, so I just let the iPod shuffle hang from it since it seems light enough and the cord seems strong enough for it). It seems to charge fine, according to the iTunes UI. To cut to the chase, my question is, is it safe to leave this charging while I do anything from just browsing the internet to playing a tasking game? Is there any risk of my PSU not being able to somehow handle it? Basically, should I leave it charging while I'm not using the computer to be safe or can I just do whatever while I let it charge? I'd assume the latter, since Apple devices aren't exactly made for the type of people that would think about these sorts of things, but I want to be sure just in case. It's an ASUS M51AD desktop computer, if that's relevant info.

Answer 1

The power available to USB is fairly tightly controlled so, no, it is unlikely to have any impact at all even if you have lots of things plugged in to different USB ports. Of course, unless it is one of the "special" USB ports, it will power off when you power off (or put to sleep) the computer.

However, leaving the iPod dangling from the connector is VERY likely to damage at least the cable if not the iPod connector over time. Not a good idea I'm afraid. It could also damage the USB connector on the computer.

Answer 2

It will not damage your computer under normal circumstance.

Even in a situation where your power supply was just barley covering what it needed to run your computer, plugging in your ipod at that point would not crash/damage it. You simply would't have enough available power for your USB ports to function properly and your ipod would not connect or would connect for a second and drop out.

Answer 3

Current USB will not draw more than 5 or 10 Watt power on any device, depending on the USB port and the device. Some tablets charge at 10 Watt if the USB port provides 10 Watt, which it usually does not. The USB port might also safely provide less than 5 Watt, the exact power draw is negotiated over the USB protocol. The weakest PSU you'll find in a desktop PC provides 200 Watt, the stronger ones are over 500 Watt. Your desktop has a 500 Watt PSU, and judging from the components it's built with it will probably only use 350 W under full load.

This will change with the new USB spec which allows USB to provide up to 100 W, but first of all the actual power draw is still negotiated, and second your device doesn't support the new spec.