XO battery/performance [Devel Digest, Vol 76, Issue 21]

Richard A. Smith richard at laptop.org
Sun Jul 22 12:56:56 EDT 2012

On 07/21/2012 12:53 PM, Yioryos Asprobounitis wrote:

> I'm sorry but I did not run any  bg-acr! commands except the one you
>  suggested. The only command that I run outside your suggestions is
> bg-acr@ .bg-acr with no batman.fth/batman-start first, which
> certainly can not account for the erratic behavior.

Commands _like_ 'bg-acr!' that includes all of the bg-* commands and 
many others.  They _require_ batman-start to function.  If it hasn't 
been called then they do it for you.  Thus if you have run those command 
and not run batman-stop then the charging system will behave 
erratically.  bg-acr! changes values that take the EC close to a full 
cycle to recovery from so even after a full reset the reporting can be 

> I keep saying that the battery EC might have a problem

There is no battery EC.  The battery only has a sensor chip. The EC on 
the XO talks to that chip and reads voltage, current, temperature, ACR 
and a few other values.

> and you just
> dismiss all the indications (like a full battery reporting as empty)

I'm sorry if my last mail came across the wrong way I was in a bit of a 
hurry before my flight.

Its just that I keep telling you that nothing you have presented so far 
indicates there is a communication problem between the EC and battery. 
I'll be the very first to tell you when I see something I think is 
funky.  Just like with the rollover bug.

I'm not dismissing what you say. I'm just trying to tell you that you 
aren't doing anything useful debugging wise when you try to figure out 
whats going on based on the charging LED or what sugar tells you.  The 
use of _any_ of the debugging commands I gave you will screw up the 
normal battery reporting.

If you want to known whats happening when you boot Linux then please do 
a full power cycle and run olpc-pwr-log.  Those log files are much, 
much, more useful than what the LED/Sugar is doing.  The LED/sugar can 
lie to you but the log files do not.  Normally, I boot the laptop 
without the battery installed, run olpc-pwr-log and then insert the 
battery. olpc-pwr-log will wait for a battery to show up.

>  including even the fact that EC reports the battery is asleep while
>  the discharge data show that is not.

Its not possible for the battery to go to sleep.  I don't understand 
what you are referring to.

> Oh well, I do not think that one battery in a couple of millions
> worths all this trouble.

Actually I believe it is worth the trouble because there is never just a 
single problem that doesn't happen to another machine.  If you have this 
failure then there are probably many more.  Its just never been reported.

I'm happy to keep working on this if you don't mind the time.

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

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