[Gta04-owner] various powermanagement issues

H. Nikolaus Schaller hns at goldelico.com
Fri Oct 16 20:05:07 CEST 2015

Hi Andreas,
I will try to answer some.

Am 15.10.2015 um 17:12 schrieb Andreas Kemnade <andreas at kemnade.info>:

> Hi,
> I have several questions regarding power management. Just the very,
> very basic stuff.
> About letting power into the gta04:
> I had my usb socket broken, pads for the case pads were completely
> rip off, so the charging via usb did not work. I noticed that issue at
> the beginning of my bicycle trip when I left the ferry...
> - If such things do not happen at home, where do you get that fixed?

Well, by a GTA04A5. It will have an USB socket that is manually soldered
through the PCB. Ripping it off is much more difficult.
> - What kind of mistreatment causes that problem?

If you have the USB connector plugged in and bend it too much up or down.

But in my experience it mainly happens when opening the plasics case and
removing the PCB.

> - My externol charger did not load a BL6C replacement I finally found 
>  (the idea mas to charge one and use the other).
>  That seems to be a mechanical tolerance issue. Do these problems also
>  happen with the GTA04 itself?
> Monitoring device current:
> My last boot from flat battery took >10h even with my bike-approved
> initrd setup.

Depends if your device goes to suspend or not. If it does not, it will draw ~400mA.
And USB charging is limited to 500mA (unless increased to 800mA). So there
are 100 mA for charging of a 1200mAh battery. Should make 12 h.

> My battery seems to have lost much capacity the last
> weeks. I guess I could still find GTA02 batteries somewhere but not for
> a long time. So the questions are:
> - Are there any other hints for current other than montioring IUOS
> mhile in CV charge mode?

bq27000 through hqd should report.

> - Has anyone designed things like a BQ27000 adaptor to put a little bit
>  smaller standard battery into the GTA04 and that adaptor between the
>  adaptor board?

Not that I am aware of. But it is an interesting idea! You would just have to design
a tiny PCB with two spring contacts on one side and 3 gold contacts on the other.
A shunt resistor and the bq27000 in between. Maybe even embedded in the
PCB (which should be just 0.5mm thickness...).

But beware to make it short-circuit *safe*. And, you have to program the bq27000
so that it "knows" the nominal capacity. I don't know how easily that can be done.

Or wait for the GTA04A5. It will have a bq27621 system side fuel gauge (full
Linux driver is coming with 4.4-rc1).


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