| Ron Hunter 2007-05-30, 7:33 am |
| sarah bennett wrote:
> On Tue, 29 May 2007 05:54:44 -0500, Ron Hunter wrote:
>
>
> Hi there Ron,
> I almost agree. Sure, a modern USB cable must be cheap to the manufacturer.
> Probably the printing on the box costs more than it does to supply a modern
> mass-produced USB cable.
>
> But, a cable won't ALWAYS work!
>
> The one caveat you MUST keep in mind for MOST (all?) modern portable
> devices which use USB to charge is that the USB 2.0 PC will NOT charge a
> completely dead portable device. Yup. The reason is that the device has to
> TELL the PC to output the power to charge versus just supplying two-way
> data transfer. Basically the portable GPS unit must ASK for power from the
> PC! If it's completely dead, it can't do that.
>
> While 95% of the time your modern portable device won't be COMPLETELY dead,
> to plan for the other 5%, you'll need the modern AC or DC mini-USB adapter
> in addition to the PC cable.
>
> I'm sure there are people on this newsgroup who know the USB specification
> better than I so please correct me if I'm wrong that a PC cable won't
> charge modern electronics if the portable device is completely dead.
>
> Maybe there is a way in PC software to TELL the USB device to output the
> power in that case? Do experts on this newsgroup know?
>
> sarah
It isn't possible in normal use to completely discharge the battery in
my GPS, or cell-phones. They shut off when the battery voltage gets
critical.
|