[Power] Checking the life battery of XOs batteries deployed after 3 years of usage

[Richard A. Smith]

On 05/15/2013 04:25 PM, Xavier Carcelle wrote:

> Very accurate infos. These data are written into the eeprom by which
> process ? reading info from the batteries that are written into eeprom
> through one-wire ? spi ?

The eeprom inside the battery gauge contains very little data that is of 
importance to anything except the EC battery code.  The mechanism is via 
the olpc battery driver which talks to the EC via EC commands.  All the 
in the log are not eeprom values but rather the decoded values from 
registers in the battery gauge chip. ie voltage, current, ACR.  The EC 
reads these registers from the battery via one-wire and then the kernel 
gets them from the EC via the command channel.

>> 2) Disable auto power management (if enabled)
> how do i know if this is enable/disable on my XO ?

Power management is disabled by default on an XO-1 so unless you turned 
it on its off.  XO-1.5s shipped with power management enabled.

You can tell if its enabled by looking in the sugar control panel.

http://wiki.laptop.org/go/Sugar_Control_Panel#Automatic_power_management

> We have decided to backup all 200+ XOs power-logs so I will tarball
> everything over the next days but here are sample for first approach
> of the data.

Great.  Thank you.

>> I have python tool(s) for processing files in build or for looking at
>> various things.  Let me know if you want to learn how to use them.
>> Net mAh however should give you a good indication of your current
>> capacity.
>
> Would it be possible to test your python tool also over our logs and
> get some feedbacks of the batteries ?

We can for log files that have enough battery runtime.  Looking at the 
sample log files you sent most of them are when the laptop is connected 
to external power.  In that case there isn't much power usage information.

>
> Excellent, we should find out interesting data from our logs and maybe
> extract the low level batteries. Is there a way to desulfate or
> regenerate some of the insider liquid/acid of the batteries ?

Nope.  LiFePO4 batteries do not have those issues.  There were some 
problems with cell balancing on early XO-1 batteries but if you were 
having problem with that you would probably have noticed.  Batteries 
that have a capacity that has dropped to below what you consider a 
usable level should be recycled and new ones purchased.

Log files that have long runs of where the XO is on battery only should 
be able to give you an approximate battery capacity.

> any RMA
> for the OLPC fondation on the batteries ?

Nope.

> Lionel told me that you will be in Paris early June and we could meet
> up to share experiences about power and OLPC deployments ?

Yes I'll be there but only briefly.  I'll be on vacation in London and 
my girlfriend and I decided to take an overnight trip to Paris.  We 
arrive June 5th (noonish) plan to spend the day wandering around, and 
then leave the morning of the 6th.  We are planning to have a dinner 
with a friend of mine on the 6th.  We want to go to a good Raclette 
place but have not yet decided where.  You are welcome to join us for 
dinner and/or drinks before hand.   I'll email you off list to work out 
the details.

-- 
Richard A. Smith  <richard at laptop.org>
One Laptop per Child