[Trac #687] battery overcharge conditions still exist

[Zarro Boogs per Child]

#687: battery overcharge conditions still exist
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 Reporter:  rsmith               |       Owner:  ted.juan
     Type:  defect               |      Status:  new     
 Priority:  blocker              |   Milestone:  BTest-2 
Component:  embedded controller  |    Keywords:          
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 I've found a battery here at OLPC that still gets overcharged.

 BIOS firmware was Q2B16 which has the latest EC firmware.

 While talking to John (J5) in the Redhat room I noticed some strange thing
 happing with the battery light on his XO.

 It was cycling colors.  Off, yellow, green, off, yellow, green over and
 over.

 off and green lasted about 1 second while yellow would last anywhere from
 1 to 3 seconds.

 So I started monitoring the output of capacity_percentage, voltage,
 current, and temp1 from the /sys/class/battery/psu_0 directory.

 I found that the capacity_percentage was switching from 6 to 91 roughly
 correlating to the yellow  and green states of the battery led.

 Voltage, current, and temp1 were constant.  7528, 760, and 39237
 respectively.

 I then removed AC from the unit.  Battery light started flashing red
 and I got the following readings..
 Cap,V,I,Temp
 6,7499,749,40628

 If I plugged AC backup I got the cyclic off,yellow,green with capacitys
 back between 6 and 91.

 I did this back and forth (AC, No AC) a few times and got consistent
 results.

 Then I plugged AC backup and started watching temp1.   Temp1 continued to
 rise until it reached > 45000 and I removed the AC plug.  The XO instantly
 shut off.  After that if I tried to turn it on it would immediately turn
 back off.

 So I pull the battery and let it sit for 5 seconds or so, plugged the
 battery back in and started the XO back up.  It booed up with the battery
 led blinking red.

 I then dumped Cap, V, I, and T,
 0,6970,-1122,43726

 Then I plugged AC back up.  Battery led stayed yellow for a while but then
 it started the off,yellow,green cycle.  Temp1 dropped down to about 40035
 but then began to climb again.  I turned it off when it rose above 43000

 Then I swapped the batteries with another XO that had Q2B16 and a fully
 charged battery.  The original XO behaved normally and the XO that I
 traded batteries with started doing the same off,yellow, green  cycle and
 temp1 rose from 40 C to 41 C.

 I then cooled the battery to 25C (put it in the freezer for a bit) and
 replaced it back into the   XO and observed exactly the same results as
 when the battery was hot.

 So I appear to have a magic battery that will cause an overcharge
 condition to occur.

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Ticket URL: <http://dev.laptop.org/ticket/687>
One Laptop Per Child <http://laptop.org/>