Re: charging phone on usb harmful?

If your machine is off, but still plugged in, you shouldn't lose your CMOS
settings.  The CMOS settings are kept by the battery when unplugged, and by
"standby power" from the power supply when plugged in.

Standby power is on even when the computer is off.  Some power supplies
have a switch on the back of them which turns off standby power, tho.

Realistically, if you're losing time when your computer is off but plugged
in, the battery *might* be the problem (it could have died with a short).
It would be a little unusual, tho.

I guess it's *technically* possible for a USB device to cause this problem.
Both the CMOS/RTC and USB are powered from the 5V rail.  But you'd have to
do something really weird which drove too much power back into the
computer.  Just charging your phone shouldn't be able to cause this
problem.  If you drew too much power, you might be able to get your
computer to reboot/hang or something like that, but causing permanent
damage to your RTC just seems extremely unlikely.

That all said, the RTC in a PC is terrible.  I always write time from a NTP
server on boot for every machine I own, as a matter of policy.

Matt

On Tue, Sep 18, 2007 at 09:21:12AM -0700, Stephen Samuel wrote:
> If you're replacing the battery:
> 1) make sure the machine is off, and
> 2) write down any wierd BIOS settings in case you lose your CMOS
> memory during the change.
> 
> On 9/18/07, roel <[email protected]> wrote:
> > Is it possibly harmful for my computer to charge my phone on the USB
> > port (using a USB to mini-USB cable)? While this worked, it is possible
> > that after this the harware clock of my computer stopped working (I now
> > write time during boot using an ntp server).
> >
> > Roel
> >
> > PS I'm not on this list, so please cc.
> >
> 
> -- 
> Stephen Samuel http://www.bcgreen.com
> 778-861-7641
> 
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-- 
Matthew Dharm                              Home: [email protected] 
Maintainer, Linux USB Mass Storage Driver

SP: I sell software for Microsoft.  Can you set me free?
DP: Natural Selection says I shouldn't.
					-- MS Salesman and Dust Puppy
User Friendly, 4/2/1998

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