High current USB charging ( was: Re: Price of the Freerunner spare parts)

Michael Shiloh michael at openmoko.org
Thu Mar 27 23:38:32 CET 2008


(PLEASE CHANGE SUBJECT WHEN TOPIC CHANGES!)

I don't think the Neo would get damaged.

I think the only damage might occur to the charger, whether the charger 
is a computer or a charger only. A charger (or computer) designed to 
provide, say, 200mA might overheat if more that 200mA is drawn, possibly 
resulting in a component failure. In the worst case, something in the 
charger gets extremely hot but does not fail (or does not fail quickly), 
resulting in the possibility of a fire.

So if you enable (force) 1A charging when plugged into a computer USB 
port which can not supply 1A (which most can't), then you run the very 
real possibility of damaging your computer.

Michael

Federico Lorenzi wrote:
> I was just about to ask, what would happen if I enabled 1A charging
> when the Freerunner was plugged into a normal USB port? AFAIK some
> devices do draw more then spec (USB laptop hdds come to mind), and
> these seem to work fine.
> 
> Cheers
> Federico
> 
> On 3/27/08, Kevin Dean <kevin at foreverdean.info> wrote:
>> On Thu, Mar 27, 2008 at 2:58 PM, joerg <joerg.twinklephone at gmx.de> wrote:
>>
>>>  Correct, it checks for 48k-OHM resistor on ID-pin of mini-USB, then
>> enables 1A
>>>  instead of 100/500mA USB-standard.
>>>  You also may enable 1A-mode (and 500mA mode) via some small GUI-app IIRC.
>>>
>> This is possible via userspace with Bobby's application.
>> (http://wiki.openmoko.org/wiki/CheckFastCharge-script).
>>
>> However, the flaw to this is that it will force fast charge even if
>> the charger isn't capable and hints that this could be... bad. :)
>>
>> For the record, it APPEARS that with the Python application, the iGo
>> works just fine as a charger.
>>
>> -Kevin
>>
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