[Gta04-owner] problems with battery loading

H. Nikolaus Schaller hns at goldelico.com
Thu May 26 23:07:29 CEST 2016


> Am 26.05.2016 um 20:14 schrieb <t.munker at gmx.net> <t.munker at gmx.net>:
> Hi,
> i've got some problem with loading my battery.
> Symptoms are:
> When plugging usb line in at the phone, phone wakes up and starts
> loading, if there is power.

Even without the cable connected on the other end?

> Plugging in at the other end of the usb line is not detected (when first
> plugged in at phone, phone wakes up, but can't load since there is no
> power and goes sleeping again)
> After some seconds (mostly) (sometimes even about half an hour) it stops
> loading, even when battery capacity is still critical.

Hm. Looks like broken cable.

> Old openmoko power adapter doesn't seem to work at all.
> To get the phone usable i need to watch it closely, and unplug and
> replug it, if it stops loading.
> Environment:
> I use QTMoko. Since this has some lag until plugging is detected, i use
> neocontrol to view power status.
> I resoldered my usb-port, maybe something went wrong there. But right
> after resoldering it, it was working good and now got slowly worse...
> Also the sd-card got already corrupted at some point, i will reinstall
> next days to exclude a software error
> Where i need help:
> Is there some way to determine why the phone stops loading?

I don't know about tools but latest QtMoko still uses the old 3.7 kernel
which does not have a good charger driver. The main problem is that it simply
stops charging as soon as the USB voltage inside the GTA04 drops below
4.5V. And does not restart unless you unplug + replug the cable.

This may have a reason in a weak cable or weak power supply, especially
with almost empty battery when the charging current going through the cable
(in parallel to operating the GTA04) is highest. This may be ~800 mA...

> When i want to check my usb-port, is this possible with a simple
> ohm-/volt-/ampere-meter? What are the readings that i should expect
> between the usb-pins when connected correctly to the board?

A common source of trouble is if the GND or the shield is not really connected.
This may happen during repair. So you should check if you have
0V on GND
3.3V on data lines (may be there only for a very short test cycle so you can't notice)
ca. 1V on the ID line
5V on the VBUS line

For charging, the data lines are not used. Therefore having a good 5V input is most

> Kind regards,
> Thomas Munker
> PS: Is this the right list to write to? If not, please forward...

Yes of course... It is for GTA04 owners like you :)


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