ubuntu-phone team mailing list archive

[Selene Scriven <selene.scriven@xxxxxxxxxxxxx>]

* Matthias Apitz <guru@xxxxxxxxxxx> wrote:
> Is it possible to attach addition wires, in parallel and 
> inline, to attach meters outside the device while using or 
> charging?
> 
> I think, we need an independent measurement of the energy 
> in/out to understand if the battery firmware or the kernel 
> software is broken.

You mean like this?

  http://toykeeper.net/tmp/phablet/power/exoskeletal-krillin-power.1.jpg

I have some phones with the batteries removed and replaced by a 
bench power supply with a meter attached in the middle.  What 
I've found is that there isn't just one issue, there are several.  
There are discrepancies between the physical power device and 
what the kernel sees, for example, and between what the kernel 
sees and what the power daemon reports, and between what the 
power daemon reports and what the user can see.

Although partial solutions are possible, a complete solution 
would probably require cooperation of multiple companies at 
different parts of the stack.  Each layer of abstraction seems to 
introduce additional inaccuracies.

One thing Ubuntu could do is to remove the part which tries to 
convert kernel-reported voltage into percentage.  However, not 
many people like to see "3.82V" with no estimate for what that 
means in terms of time or percent...  and the kernel's data isn't 
entirely accurate either.

So...  long story short, it's complicated on multiple levels.

You can prolong battery life (in years) by keeping the battery 
from getting completely drained and by not leaving it plugged in 
while full.  Over-charging and over-discharging are the fastest 
ways to kill lithium ion cells.  In particular, leaving it 
plugged in all the time can cause damage.


-- Selene