USB Power hog

[Ipheuria]

So today I noticed how much of a USB power hog is the Iphone. Last week I noticed that my Iphone would connect for 5 minutes and then disconnect and re-connect over and over. It was plugged in to a USB hub along with all my other devices. So ofcourse the first thing I did was to move my Iphone to one of my laptops USB ports. It immediately stopped the disconnect and re-connect behaviour. Then I noticed that my USB mouse plugged in to the USB hub would stop working a couple times a day, today I noticed that it was every time I plugged my Iphone in to charge or sync. So looks like the Iphone sucks so much power from the USB that the hub can't get enough power for the other devices. I also noticed today when I put the phone to charge that the back gets really hot during charging, is anyone else having that problem?

 

[GMJeff]

Sometimes I have noticed the heat, but it is a intermittent thing. A USB port only puts out about 200 milliAmps anyway, not a whole lot of power. The wall charger for the iPhone puts out approximately 1 Amp.

Some of the ports on a computer do not have the full 200 mA because of other devices connected, as it appears you have found out. A hub will also have issues with power, unless it has it's own 5v power supply that plugs in the wall.

I have found USB devices to work rather poorly when there is more than one connector in between them, and the root hub on the computer. Except for maybe a memory stick or something small like that.

The iPhone definitely needs a full powered USB port.

Also, check your power management setup and be sure that the USB ports aren't going into a low power or off state to conserve power. If you are running a windows machine, go into the device manager, and under system devices (if I remember right, that is what it is called) near the bottom of the list, and expand the list. You should see some items that are listed as USB root hubs and such. On each root hub, double click on it to open the properties sheet and choose the power management tab. On this tab, uncheck the option that says "Turn this device off to save power", then apply. Do this for all of them and then close the device manager. This will manually stop all of your USB hubs from going into a sleep state while the computer is on.

Of course, if you have a Mac, just switch to a port that is not on a hub. Tower computers usually have USB ports on the back near the connectors for other various hardware. Those ports are directly connected to the motherboard and are part of the root hubs.

Sorry for the long post

 

[Ipheuria]

I have a Macbook Pro but I'm running Windows in parrallel to Mac OS. Thanks for the tip about the power state of the USB. I always turn off hibernation on Windows and use Full Power settings but I didn't turn off the low power state in Device Manager. The USB hub does have it's own power supply which is why I thought it was OK to use for all my devices but then again I have all 3 USB ports full on the laptop. Two external drives and the hub is completely full so I guess I'm drawing alot of power. I never noticed the heat before, but then never thought it would heat up during charging I was so surprised.