[Gta04-owner] charging log

Dr. H. Nikolaus Schaller hns at goldelico.com
Fri Sep 13 14:40:10 CEST 2013


Hi,

Am 13.09.2013 um 14:02 schrieb Radek Polak:

> On Monday, September 09, 2013 01:53:13 AM NeilBrown wrote:
>  
> > In Radek's logs the voltage is initially around 4.5 but then drops below
> > 4.4 while charging.  It finished the charge at aout 4.4V but it seems this
> > is too low to restart.
> > 
> > My logs show the twl4030_usb voltage between 4.81 and 5.18.
> > 
> > Possibly setting a lower charge current (via those udev rules) might allow
> > the voltage to remain high.
>  
> Hi,
> i did some progress with GTA04 charging. The initial code is now in QtMoko git tree [1]. This is how it works now:
>  
> After boot kernel draws 600mA from USB (because twl4030_charger.allow_usb=1)
>  
> QtMoko on startup sets the limit to 100mA with
>  
> 	echo N > /sys/module/twl4030_charger/parameters/allow_usb
>  
> Now when USB is plugged in charging current is set to 100mA. QtMoko slowly increases current while checking that voltage does not drop under 4.6V Once it drops it stops increasing the charging current.
>  
> On my notebook the charging current raises up to 600mA (this is limit) and there is still quite high voltage (4.8V). At work on my PC the charging current raises to 450mA and voltage is around 4.5V. This is still enough to charge the battery with 150mA. And now charging should always restart once the battery gets low.
>  
> I have also implemented slow charging when battery is above 90%. It checks battery current. When battery is charging with more then 50mA it lowers charging current. The slow charging takes ~2 hours. The idea is that in those two hours you have nearly full battery ready to use. Without slow charging it would already started discharging...
>  
> Last thing - QtMoko now logs charging and draws nice graphs in NeoControl (attached).

Nice work, but I am not sure what is going on.

I have tested at least 8 different GTA04 and none did have below 4.5V. A very typical value is like Neil did report (4.8 - 5.0V).

Did you check the cable or your power supply?

BR,
Nikolaus
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