[olpc-help] XO shuts down when power cord removed

[Richard A. Smith]

Andrew Cooper wrote:

> 
> That SO needs to be in an easily searchable FAQ!!!  It worked like charm!!  Here's what I got...
> 
> Thanks again,
> Andy

Here's my analysis of your data in time order.

1200060544,0,7055870,1322786,1992,65398,Charging,Normal
...
1200062623,21,7294380,1202343,3385,1633,Charging,Normal

Normal charge for about 35 minutes delivering 738 mA/h into the battery. 
  The voltage is higher though than I would expect.  A deeply discharged 
battery should be in the < 6V range.

On the next sample

1200062633,21,7506660,781,3377,1635,Charging,Normal
...
1200062684,81,7500560,390,3211,1635,Charging,Normal
1200062694,97,6617890,390,3176,1635,Full,Full

The voltage jumped up to 7.5V which is above the CC to CV threshold also 
notice that your current went from 1.2A to less than 1mA.  Very 
abnormal. The EC switches from constant current (CC) into constant 
voltage (CV), marks the battery as 81% full and watches the current to 
be less than 200mA.  A few cycles of that and it declares the battery Full.

Discharging...

1200064031,97,6593490,0,2277,902,Full,Full
1200064041,97,5988980,-979427,2276,897,Discharging,Full

So 20 minutes later you started the discharge in that space you seem to 
have lost 305 mA/h.  Odd but ok I guess.

1200066554,76,5612610,-1043880,2702,64814,Discharging,Normal

42 minutes of discharge until the voltage nears critical shutoff. 676 
mA/h consumed. So 676+305 = 981 mA/h. Previous charge only had 738 mA/h 
so that leaves 243 unaccounted for but thats probably close enough to match.

1200067088,,,,,,,
1200067098,0,7506050,130,2245,64951,Charging,Normal
1200067108,0,7505440,130,2236,64951,Charging,Normal
1200067119,0,7503610,390,2238,64951,Charging,Normal
1200067129,81,7508490,130,2241,64951,Charging,Normal
1200067139,81,7503610,520,2240,64951,Charging,Normal
1200067149,81,7505440,-130,2238,64951,Charging,Normal
1200067159,97,6268970,0,2237,64951,Full,Full
1200067170,97,5683370,-1002734,2242,64950,Discharging,Full
1200067180,97,5682150,-921484,2248,64944,Discharging,Full

Here's a real indicator of your troubles.  When the EC detected the 
battery (SOC % is zero so I guess you reset it with batman.fth?) the 
Voltage is 7.5V yet ACR shows that only 45 mA/h was added to the 
battery.  So the battery is still very discharged.  The voltage should 
be much lower and the current much higher.  This condition is what 
happens when a battery get close to full.  So the EC marks it as such.

The other log files are more of the same. Very short charging period 
with an abrupt voltage jump and loss of current.

Because you have one run of 35 minutes where the charging appears to 
work correctly I'm inclined to believe that this is a physical 
connection issue rather than a battery chemistry issue.  I think you 
have a bad connection somewhere in your charge path that is creating a 
high resistance and faking out the EC charging code.

How close are you to your 30 days?  If you are really close then I 
suggest you RMA it.  If not then I have one more test I'd like to try.

I'm going to hack on batman.fth and add the ability for you to _force_ 
charging. Then you can run this and watch what is happening while you 
prod, jiggle, and torque things around.  Then we can see if your 
charging current bounces around.  Try to see if we can find some sort of 
cause and effect.  If so then its a bad connection in the charge path 
somewhere.  If not then something is wonky with the battery cells.

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