[Gta04-owner] How could GTA04 shine

[Alexander Lehner]

On Thu, 8 Mar 2012, Bob Ham wrote:

>> [...]
>> Unfortunately we (still) do consume a lot more power during
>> suspend. This solution will only charge the battery (very slowly!)
>> when the device is off.
>
> Indeed, the use case I'm imagining is where the phone is off to conserve
> power and the charging simply becomes a (possibly very useful) added
> bonus.

I've been playing a lot with powering the phone (also using a hand-crank, 
see my page:http://wiki.openmoko.org/wiki/User:Blutsauger).
And it's true, it's eating a lot energy.

I also tried different things using solar charger, but they were external devices 
providing an USB output.

Example for a reasonable price (there are also some more professional 
ones above 100 EUR):
http://www.conrad.de/ce/de/product/200175/


Disadvantage of the USB slot is, that usually two Mignon cells (AA, 
2x1.2V) are used and the voltage is transformed up to 5V with a pretty bad 
power coefficient.

Putting a solar cell directly to the batterys contacts seems a super 
simple idea, but I don't know how the GTA battery behaves there, since it 
has some logics inside to measure and control charge/discharge.

I now start an experiment using 3 AAA micro batteries and shorten them to 
a 5V solar panel with 80mA nominal current (about the size of the phone).
The 3.6V deliver enough power to keep the phone alive, I've tested that
already, even if the power management complains about the missing original 
battery.

This is just a 20 EUR experiment, but thinkable - if partially successful 
- would be an alternate battery container for AAA batteries and the solar 
attached on the back.
I will order the case modding at Lukas since he's done with the 
replacement design at shapeways and needs some new work ;)

I'll let you know what the results are. OK, it's still winter and the 
sun is not very strong...


A.