[Gta04-owner] charging log

Radek Polak psonek2 at seznam.cz
Fri Sep 13 14:02:11 CEST 2013


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).

Regards

Radek


[1] 
https://github.com/radekp/qtmoko/blob/master/devices/gta04/server/neohardware.cpp
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