You need an energy harvester ic in order to make this work.

Have a look here https://www.youtube.com/watch?v=lrELRVFEx_s

I would personally use LTC3105
http://www.linear.com/product/LTC3105

Hi,
it seems that my first version had swapped + and - although i have checked several times i did it wrong

Yesterday i redid the whole thing from scratch again. This time i used plasticine for precise copper stripes position and verified with 4.5V battery that charging works - and it worked.

After attaching solar panels it showed no activity under lamp, but later on direct sun the phone vibrated and displayed charging dialog + the white led was shining.

This is ok, but i havent seen that battery charge raised. In idle my jolla normally eats ~7mA, the panels should deliver 25mA so the charging current should be ~18mA. But i wonder if the phone is really idle while charging. And i wonder how to measure it...

Thanks for the link - interesting, but i wonder if it will fit somewhere under the cover...

To get 1% more charge (21 mAh), you have to keep the panels in direct sunlight for over an hour.
18 mA is very very slow charging rate.

Did you mean 21 mAh ?

Indeed. Assuming 6V (being generous here, the real voltage must be much lower), it means only 150 mW (6V x 25 mA). That's about an order of magnitude less than what I would expect. Either the light level was very low or the panels are too small (covering less than 10% of the back space), particularly poor quality or damaged by the previous experiment with reversed polarity.

Yeah

@psonek, could you look what the phone says about the voltage now that the polarity is right (cat /sys/devices/platform/msm_ssbi.0/pm8038-core/pm8xxx-adc/dcin)?

I'm a bit afraid the whole thing will become hot. When I put my WakaWaka in the sun, it will be hot in an hour. Make the solar panel or the OH detachable so the phone can get some shade?

ehhh



isn't this the case for every solar oh??

either
-accept it (join the sunny side)
or
-make a detachable third-half with solar panel and battery

[root@jolla nemo]# cat /sys/devices/platform/msm_ssbi.0/pm8038-core/pm8xxx-adc/dcin
Result:4314054 Raw:32057
[root@jolla nemo]# cat /sys/devices/platform/msm_ssbi.0/pm8038-core/pm8xxx-adc/dcin
Result:4514790 Raw:32399

Mostly the values seem to be between 4.3V and 4.5V

Hi,
after a few days i still have not seen the battery being really charged with my solar toh.

I wonder where is problem. Battery status is "Charging", but current_now is never negative. Even more interestingly while charging it seems to consume more power.

In dark on wifi ssh i get values like this:

[nemo@jolla ~]$ cat /sys/class/power_supply/battery/current_now
2595

[nemo@jolla ~]$ cat /sys/class/power_supply/battery/current_now
8415

Under lamp while solar charging:

[nemo@jolla ~]$ cat /sys/class/power_supply/battery/current_now
10618

[nemo@jolla ~]$ cat /sys/class/power_supply/battery/current_now
11876

Maybe while charging the phone wont enter deep sleep?