[Trac #611] Battery remaining capacity percentage constant 100% while discharging

[Zarro Boogs per Child]

#611: Battery remaining capacity percentage constant 100% while discharging
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 Reporter:  hai       |        Owner:  mfoster
     Type:  defect    |       Status:  new    
 Priority:  blocker   |    Milestone:  BTest-2
Component:  hardware  |   Resolution:         
 Keywords:            |  
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Comment (by mfoster):

 Hi, Hai!

 The current EC code release has a number of bugs, unfortunately, in its
 charge and discharge monitoring.  I've forwarded these issues to Quanta as
 HIGH-PRIORITY, so well hopefully see some significant improvement soon.

 In Quanta's defense, the EC (Embedded Controller) code is attempting the
 nearly impossible.  When a gas gauge solution was added to the battery
 pack, a well intended, but misguided, cost reduction occurred, and a
 sensor-only chip was added to the pack, which measures only voltage-
 current-temperature.  As those of us who've been around for a while
 learned long ago, the only way to do this with any reliability is instead
 to include a "coulomb counter" which actually counts electrons flowing
 back and forth - then we can give a far more reliable gas gauge.

 It's too late to fix this properly for B2, but we'll do two things.
 First, for the short term, we'll remove the special "capacity reserve"
 functionality that we're pursuing to get 2,000 cycle battery life, and
 second, we'll include a real gas gauge chip in the packs for the B3 build.

 Thanks for the feedback!

 Cheers!
 MarkF

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Ticket URL: <http://dev.laptop.org/ticket/611#comment:3>
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